lttng: move parse_userspace_probe_opts to a common util
authorJonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Thu, 27 Aug 2020 19:07:06 +0000 (15:07 -0400)
committerJérémie Galarneau <jeremie.galarneau@efficios.com>
Fri, 12 Feb 2021 20:11:08 +0000 (15:11 -0500)
parse_userspace_probe_opts will be reused for trigger creation.

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I377e0a59786794a74a9b0a7787b6f9a221245df1

src/bin/lttng/Makefile.am
src/bin/lttng/commands/enable_events.c
src/bin/lttng/uprobe.c [new file with mode: 0644]
src/bin/lttng/uprobe.h [new file with mode: 0644]

index 5c0356276f21ce8f9dabcb53da4af59bf52e5ce9..c630c6d5cb3ad963052dcd9bc229f7e5954c2b6e 100644 (file)
@@ -31,7 +31,8 @@ lttng_SOURCES = command.h conf.c conf.h commands/start.c \
                                commands/clear.c \
                                loglevel.c loglevel.h \
                                utils.c utils.h \
-                               lttng.c
+                               lttng.c \
+                               uprobe.c uprobe.h
 
 lttng_CFLAGS = $(AM_CFLAGS) $(POPT_CFLAGS)
 
index 570a3a6428cefaf132332996eefbb2aecd04ffa2..3286defc314d3d72d410125fed2194462fb1cc75 100644 (file)
@@ -30,6 +30,7 @@
 
 #include "../command.h"
 #include "../loglevel.h"
+#include "../uprobe.h"
 
 #if (LTTNG_SYMBOL_NAME_LEN == 256)
 #define LTTNG_SYMBOL_NAME_LEN_SCANF_IS_A_BROKEN_API    "255"
@@ -177,393 +178,6 @@ end:
        return ret;
 }
 
-/*
- * Walk the directories in the PATH environment variable to find the target
- * binary passed as parameter.
- *
- * On success, the full path of the binary is copied in binary_full_path out
- * parameter. This buffer is allocated by the caller and must be at least
- * LTTNG_PATH_MAX bytes long.
- * On failure, returns -1;
- */
-static int walk_command_search_path(const char *binary, char *binary_full_path)
-{
-       char *tentative_binary_path = NULL;
-       char *command_search_path = NULL;
-       char *curr_search_dir_end = NULL;
-       char *curr_search_dir = NULL;
-       struct stat stat_output;
-       int ret = 0;
-
-       command_search_path = lttng_secure_getenv("PATH");
-       if (!command_search_path) {
-               ret = -1;
-               goto end;
-       }
-
-       /*
-        * Duplicate the $PATH string as the char pointer returned by getenv() should
-        * not be modified.
-        */
-       command_search_path = strdup(command_search_path);
-       if (!command_search_path) {
-               ret = -1;
-               goto end;
-       }
-
-       /*
-        * This char array is used to concatenate path to binary to look for
-        * the binary.
-        */
-       tentative_binary_path = zmalloc(LTTNG_PATH_MAX * sizeof(char));
-       if (!tentative_binary_path) {
-               ret = -1;
-               goto alloc_error;
-       }
-
-       curr_search_dir = command_search_path;
-       do {
-               /*
-                * Split on ':'. The return value of this call points to the
-                * matching character.
-                */
-               curr_search_dir_end = strchr(curr_search_dir, ':');
-               if (curr_search_dir_end != NULL) {
-                       /*
-                        * Add a NULL byte to the end of the first token so it
-                        * can be used as a string.
-                        */
-                       curr_search_dir_end[0] = '\0';
-               }
-
-               /* Empty the tentative path */
-               memset(tentative_binary_path, 0, LTTNG_PATH_MAX * sizeof(char));
-
-               /*
-                * Build the tentative path to the binary using the current
-                * search directory and the name of the binary.
-                */
-               ret = snprintf(tentative_binary_path, LTTNG_PATH_MAX, "%s/%s",
-                               curr_search_dir, binary);
-               if (ret < 0) {
-                       goto free_binary_path;
-               }
-               if (ret < LTTNG_PATH_MAX) {
-                        /*
-                         * Use STAT(2) to see if the file exists.
-                        */
-                       ret = stat(tentative_binary_path, &stat_output);
-                       if (ret == 0) {
-                               /*
-                                * Verify that it is a regular file or a
-                                * symlink and not a special file (e.g.
-                                * device).
-                                */
-                               if (S_ISREG(stat_output.st_mode)
-                                               || S_ISLNK(stat_output.st_mode)) {
-                                       /*
-                                        * Found a match, set the out parameter
-                                        * and return success.
-                                        */
-                                       ret = lttng_strncpy(binary_full_path,
-                                                       tentative_binary_path,
-                                                       LTTNG_PATH_MAX);
-                                       if (ret == -1) {
-                                               ERR("Source path does not fit "
-                                                       "in destination buffer.");
-                                       }
-                                       goto free_binary_path;
-                               }
-                       }
-               }
-               /* Go to the next entry in the $PATH variable. */
-               curr_search_dir = curr_search_dir_end + 1;
-       } while (curr_search_dir_end != NULL);
-
-free_binary_path:
-       free(tentative_binary_path);
-alloc_error:
-       free(command_search_path);
-end:
-       return ret;
-}
-
-/*
- * Check if the symbol field passed by the user is in fact an address or an
- * offset from a symbol. Those two instrumentation types are not supported yet.
- * It's expected to be a common mistake because of the existing --probe option
- * that does support these formats.
- *
- * Here are examples of these unsupported formats for the --userspace-probe
- * option:
- * elf:/path/to/binary:0x400430
- * elf:/path/to/binary:4194364
- * elf:/path/to/binary:my_symbol+0x323
- * elf:/path/to/binary:my_symbol+43
- */
-static int warn_userspace_probe_syntax(const char *symbol)
-{
-       int ret;
-
-       /* Check if the symbol field is an hex address. */
-       ret = sscanf(symbol, "0x%*x");
-       if (ret > 0) {
-               /* If there is a match, print a warning and return an error. */
-               ERR("Userspace probe on address not supported yet.");
-               ret = CMD_UNSUPPORTED;
-               goto error;
-       }
-
-       /* Check if the symbol field is an decimal address. */
-       ret = sscanf(symbol, "%*u");
-       if (ret > 0) {
-               /* If there is a match, print a warning and return an error. */
-               ERR("Userspace probe on address not supported yet.");
-               ret = CMD_UNSUPPORTED;
-               goto error;
-       }
-
-       /* Check if the symbol field is symbol+hex_offset. */
-       ret = sscanf(symbol, "%*[^+]+0x%*x");
-       if (ret > 0) {
-               /* If there is a match, print a warning and return an error. */
-               ERR("Userspace probe on symbol+offset not supported yet.");
-               ret = CMD_UNSUPPORTED;
-               goto error;
-       }
-
-       /* Check if the symbol field is symbol+decimal_offset. */
-       ret = sscanf(symbol, "%*[^+]+%*u");
-       if (ret > 0) {
-               /* If there is a match, print a warning and return an error. */
-               ERR("Userspace probe on symbol+offset not supported yet.");
-               ret = CMD_UNSUPPORTED;
-               goto error;
-       }
-
-       ret = 0;
-
-error:
-       return ret;
-}
-
-/*
- * Parse userspace probe options
- * Set the userspace probe fields in the lttng_event struct and set the
- * target_path to the path to the binary.
- */
-static int parse_userspace_probe_opts(struct lttng_event *ev, char *opt)
-{
-       int ret = CMD_SUCCESS;
-       int num_token;
-       char **tokens;
-       char *target_path = NULL;
-       char *unescaped_target_path = NULL;
-       char *real_target_path = NULL;
-       char *symbol_name = NULL, *probe_name = NULL, *provider_name = NULL;
-       struct lttng_userspace_probe_location *probe_location = NULL;
-       struct lttng_userspace_probe_location_lookup_method *lookup_method =
-                       NULL;
-
-       if (opt == NULL) {
-               ret = CMD_ERROR;
-               goto end;
-       }
-
-       switch (ev->type) {
-       case LTTNG_EVENT_USERSPACE_PROBE:
-               break;
-       default:
-               assert(0);
-       }
-
-       /*
-        * userspace probe fields are separated by ':'.
-        */
-       tokens = strutils_split(opt, ':', 1);
-       num_token = strutils_array_of_strings_len(tokens);
-
-       /*
-        * Early sanity check that the number of parameter is between 2 and 4
-        * inclusively.
-        * elf:PATH:SYMBOL
-        * std:PATH:PROVIDER_NAME:PROBE_NAME
-        * PATH:SYMBOL (same behavior as ELF)
-        */
-       if (num_token < 2 || num_token > 4) {
-               ret = CMD_ERROR;
-               goto end_string;
-       }
-
-       /*
-        * Looking up the first parameter will tell the technique to use to
-        * interpret the userspace probe/function description.
-        */
-       switch (num_token) {
-       case 2:
-               /* When the probe type is omitted we assume ELF for now. */
-       case 3:
-               if (num_token == 3 && strcmp(tokens[0], "elf") == 0) {
-                       target_path = tokens[1];
-                       symbol_name = tokens[2];
-               } else if (num_token == 2) {
-                       target_path = tokens[0];
-                       symbol_name = tokens[1];
-               } else {
-                       ret = CMD_ERROR;
-                       goto end_string;
-               }
-               lookup_method =
-                       lttng_userspace_probe_location_lookup_method_function_elf_create();
-               if (!lookup_method) {
-                       WARN("Failed to create ELF lookup method");
-                       ret = CMD_ERROR;
-                       goto end_string;
-               }
-               break;
-       case 4:
-               if (strcmp(tokens[0], "sdt") == 0) {
-                       target_path = tokens[1];
-                       provider_name = tokens[2];
-                       probe_name = tokens[3];
-               } else {
-                       ret = CMD_ERROR;
-                       goto end_string;
-               }
-               lookup_method =
-                       lttng_userspace_probe_location_lookup_method_tracepoint_sdt_create();
-               if (!lookup_method) {
-                       WARN("Failed to create SDT lookup method");
-                       ret = CMD_ERROR;
-                       goto end_string;
-               }
-               break;
-       default:
-               ret = CMD_ERROR;
-               goto end_string;
-       }
-
-       /* strutils_unescape_string allocates a new char *. */
-       unescaped_target_path = strutils_unescape_string(target_path, 0);
-       if (!unescaped_target_path) {
-               ret = CMD_ERROR;
-               goto end_destroy_lookup_method;
-       }
-
-       /*
-        * If there is not forward slash in the path. Walk the $PATH else
-        * expand.
-        */
-       if (strchr(unescaped_target_path, '/') == NULL) {
-               /* Walk the $PATH variable to find the targeted binary. */
-               real_target_path = zmalloc(LTTNG_PATH_MAX * sizeof(char));
-               if (!real_target_path) {
-                       PERROR("Error allocating path buffer");
-                       ret = CMD_ERROR;
-                       goto end_destroy_lookup_method;
-               }
-               ret = walk_command_search_path(unescaped_target_path, real_target_path);
-               if (ret) {
-                       ERR("Binary not found.");
-                       ret = CMD_ERROR;
-                       goto end_destroy_lookup_method;
-               }
-       } else {
-               /*
-                * Expand references to `/./` and `/../`. This function does not check
-                * if the file exists. This call returns an allocated buffer on
-                * success.
-                */
-               real_target_path = utils_expand_path_keep_symlink(unescaped_target_path);
-               if (!real_target_path) {
-                       ERR("Error expanding the path to binary.");
-                       ret = CMD_ERROR;
-                       goto end_destroy_lookup_method;
-               }
-
-               /*
-                * Check if the file exists using access(2), If it does not,
-                * return an error.
-                */
-               ret = access(real_target_path, F_OK);
-               if (ret) {
-                       ERR("Cannot find binary at path: %s.", real_target_path);
-                       ret = CMD_ERROR;
-                       goto end_destroy_lookup_method;
-               }
-       }
-
-       switch (lttng_userspace_probe_location_lookup_method_get_type(lookup_method)) {
-       case LTTNG_USERSPACE_PROBE_LOCATION_LOOKUP_METHOD_TYPE_FUNCTION_ELF:
-               /*
-                * Check for common mistakes in userspace probe description syntax.
-                */
-               ret = warn_userspace_probe_syntax(symbol_name);
-               if (ret) {
-                       goto end_destroy_lookup_method;
-               }
-
-               probe_location = lttng_userspace_probe_location_function_create(
-                               real_target_path, symbol_name, lookup_method);
-               if (!probe_location) {
-                       WARN("Failed to create function probe location");
-                       ret = CMD_ERROR;
-                       goto end_destroy_lookup_method;
-               }
-
-               /* Ownership transferred to probe_location. */
-               lookup_method = NULL;
-
-               ret = lttng_event_set_userspace_probe_location(ev, probe_location);
-               if (ret) {
-                       WARN("Failed to set probe location on event");
-                       ret = CMD_ERROR;
-                       goto end_destroy_location;
-               }
-               break;
-       case LTTNG_USERSPACE_PROBE_LOCATION_LOOKUP_METHOD_TYPE_TRACEPOINT_SDT:
-               probe_location = lttng_userspace_probe_location_tracepoint_create(
-                               real_target_path, provider_name, probe_name, lookup_method);
-               if (!probe_location) {
-                       WARN("Failed to create function probe location");
-                       ret = CMD_ERROR;
-                       goto end_destroy_lookup_method;
-               }
-
-               /* Ownership transferred to probe_location. */
-               lookup_method = NULL;
-
-               ret = lttng_event_set_userspace_probe_location(ev, probe_location);
-               if (ret) {
-                       WARN("Failed to set probe location on event");
-                       ret = CMD_ERROR;
-                       goto end_destroy_location;
-               }
-               break;
-       default:
-               ret = CMD_ERROR;
-               goto end_destroy_lookup_method;
-       }
-
-       /* Successful parsing, now clean up everything and return. */
-       goto end_string;
-
-end_destroy_location:
-       lttng_userspace_probe_location_destroy(probe_location);
-end_destroy_lookup_method:
-       lttng_userspace_probe_location_lookup_method_destroy(lookup_method);
-end_string:
-       strutils_free_null_terminated_array_of_strings(tokens);
-       /*
-        * Freeing both char * here makes the error handling simplier. free()
-        * performs not action if the pointer is NULL.
-        */
-       free(real_target_path);
-       free(unescaped_target_path);
-end:
-       return ret;
-}
-
 static
 const char *print_channel_name(const char *name)
 {
@@ -788,6 +402,7 @@ static int enable_events(char *session_name)
        struct lttng_event *ev;
        struct lttng_domain dom;
        char **exclusion_list = NULL;
+       struct lttng_userspace_probe_location *uprobe_loc = NULL;
 
        memset(&dom, 0, sizeof(dom));
 
@@ -1192,7 +807,9 @@ static int enable_events(char *session_name)
                                }
                                break;
                        case LTTNG_EVENT_USERSPACE_PROBE:
-                               ret = parse_userspace_probe_opts(ev, opt_userspace_probe);
+                               assert(ev->type == LTTNG_EVENT_USERSPACE_PROBE);
+
+                               ret = parse_userspace_probe_opts(opt_userspace_probe, &uprobe_loc);
                                if (ret) {
                                        switch (ret) {
                                        case CMD_UNSUPPORTED:
@@ -1209,6 +826,16 @@ static int enable_events(char *session_name)
                                        }
                                        goto error;
                                }
+
+                               ret = lttng_event_set_userspace_probe_location(ev, uprobe_loc);
+                               if (ret) {
+                                       WARN("Failed to set probe location on event");
+                                       ret = CMD_ERROR;
+                                       goto error;
+                               }
+
+                               /* Ownership of the uprobe location was transferred to the event. */
+                               uprobe_loc = NULL;
                                break;
                        case LTTNG_EVENT_FUNCTION:
                                ret = parse_probe_opts(ev, opt_function);
@@ -1542,6 +1169,7 @@ error:
        }
        lttng_destroy_handle(handle);
        strutils_free_null_terminated_array_of_strings(exclusion_list);
+       lttng_userspace_probe_location_destroy(uprobe_loc);
 
        /* Overwrite ret with error_holder if there was an actual error with
         * enabling an event.
diff --git a/src/bin/lttng/uprobe.c b/src/bin/lttng/uprobe.c
new file mode 100644 (file)
index 0000000..c51c44a
--- /dev/null
@@ -0,0 +1,387 @@
+/*
+ * Copyright (C) 2020 EfficiOS, Inc.
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ *
+ */
+
+#include "uprobe.h"
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "common/compat/getenv.h"
+#include "common/string-utils/string-utils.h"
+#include "common/utils.h"
+#include "lttng/constant.h"
+
+#include "command.h"
+
+/*
+ * Walk the directories in the PATH environment variable to find the target
+ * binary passed as parameter.
+ *
+ * On success, the full path of the binary is copied in binary_full_path out
+ * parameter. This buffer is allocated by the caller and must be at least
+ * LTTNG_PATH_MAX bytes long.
+ * On failure, returns -1;
+ */
+static
+int walk_command_search_path(const char *binary, char *binary_full_path)
+{
+       char *tentative_binary_path = NULL;
+       char *command_search_path = NULL;
+       char *curr_search_dir_end = NULL;
+       char *curr_search_dir = NULL;
+       struct stat stat_output;
+       int ret = 0;
+
+       command_search_path = lttng_secure_getenv("PATH");
+       if (!command_search_path) {
+               ret = -1;
+               goto end;
+       }
+
+       /*
+        * Duplicate the $PATH string as the char pointer returned by getenv() should
+        * not be modified.
+        */
+       command_search_path = strdup(command_search_path);
+       if (!command_search_path) {
+               ret = -1;
+               goto end;
+       }
+
+       /*
+        * This char array is used to concatenate path to binary to look for
+        * the binary.
+        */
+       tentative_binary_path = zmalloc(LTTNG_PATH_MAX * sizeof(char));
+       if (!tentative_binary_path) {
+               ret = -1;
+               goto alloc_error;
+       }
+
+       curr_search_dir = command_search_path;
+       do {
+               /*
+                * Split on ':'. The return value of this call points to the
+                * matching character.
+                */
+               curr_search_dir_end = strchr(curr_search_dir, ':');
+               if (curr_search_dir_end != NULL) {
+                       /*
+                        * Add a NULL byte to the end of the first token so it
+                        * can be used as a string.
+                        */
+                       curr_search_dir_end[0] = '\0';
+               }
+
+               /* Empty the tentative path */
+               memset(tentative_binary_path, 0, LTTNG_PATH_MAX * sizeof(char));
+
+               /*
+                * Build the tentative path to the binary using the current
+                * search directory and the name of the binary.
+                */
+               ret = snprintf(tentative_binary_path, LTTNG_PATH_MAX, "%s/%s",
+                               curr_search_dir, binary);
+               if (ret < 0) {
+                       goto free_binary_path;
+               }
+               if (ret < LTTNG_PATH_MAX) {
+                        /*
+                         * Use STAT(2) to see if the file exists.
+                        */
+                       ret = stat(tentative_binary_path, &stat_output);
+                       if (ret == 0) {
+                               /*
+                                * Verify that it is a regular file or a
+                                * symlink and not a special file (e.g.
+                                * device).
+                                */
+                               if (S_ISREG(stat_output.st_mode)
+                                               || S_ISLNK(stat_output.st_mode)) {
+                                       /*
+                                        * Found a match, set the out parameter
+                                        * and return success.
+                                        */
+                                       ret = lttng_strncpy(binary_full_path,
+                                                       tentative_binary_path,
+                                                       LTTNG_PATH_MAX);
+                                       if (ret == -1) {
+                                               ERR("Source path does not fit "
+                                                       "in destination buffer.");
+                                       }
+                                       goto free_binary_path;
+                               }
+                       }
+               }
+               /* Go to the next entry in the $PATH variable. */
+               curr_search_dir = curr_search_dir_end + 1;
+       } while (curr_search_dir_end != NULL);
+
+free_binary_path:
+       free(tentative_binary_path);
+alloc_error:
+       free(command_search_path);
+end:
+       return ret;
+}
+
+/*
+ * Check if the symbol field passed by the user is in fact an address or an
+ * offset from a symbol. Those two instrumentation types are not supported yet.
+ * It's expected to be a common mistake because of the existing --probe option
+ * that does support these formats.
+ *
+ * Here are examples of these unsupported formats for the --userspace-probe
+ * option:
+ * elf:/path/to/binary:0x400430
+ * elf:/path/to/binary:4194364
+ * elf:/path/to/binary:my_symbol+0x323
+ * elf:/path/to/binary:my_symbol+43
+ */
+static
+int warn_userspace_probe_syntax(const char *symbol)
+{
+       int ret;
+
+       /* Check if the symbol field is an hex address. */
+       ret = sscanf(symbol, "0x%*x");
+       if (ret > 0) {
+               /* If there is a match, print a warning and return an error. */
+               ERR("Userspace probe on address not supported yet.");
+               ret = CMD_UNSUPPORTED;
+               goto error;
+       }
+
+       /* Check if the symbol field is an decimal address. */
+       ret = sscanf(symbol, "%*u");
+       if (ret > 0) {
+               /* If there is a match, print a warning and return an error. */
+               ERR("Userspace probe on address not supported yet.");
+               ret = CMD_UNSUPPORTED;
+               goto error;
+       }
+
+       /* Check if the symbol field is symbol+hex_offset. */
+       ret = sscanf(symbol, "%*[^+]+0x%*x");
+       if (ret > 0) {
+               /* If there is a match, print a warning and return an error. */
+               ERR("Userspace probe on symbol+offset not supported yet.");
+               ret = CMD_UNSUPPORTED;
+               goto error;
+       }
+
+       /* Check if the symbol field is symbol+decimal_offset. */
+       ret = sscanf(symbol, "%*[^+]+%*u");
+       if (ret > 0) {
+               /* If there is a match, print a warning and return an error. */
+               ERR("Userspace probe on symbol+offset not supported yet.");
+               ret = CMD_UNSUPPORTED;
+               goto error;
+       }
+
+       ret = 0;
+
+error:
+       return ret;
+}
+
+/*
+ * Parse userspace probe options
+ * Set the userspace probe fields in the lttng_event struct and set the
+ * target_path to the path to the binary.
+ */
+LTTNG_HIDDEN
+int parse_userspace_probe_opts(const char *opt,
+               struct lttng_userspace_probe_location **probe_location)
+{
+       int ret = CMD_SUCCESS;
+       int num_token;
+       char **tokens = NULL;
+       char *target_path = NULL;
+       char *unescaped_target_path = NULL;
+       char *real_target_path = NULL;
+       char *symbol_name = NULL, *probe_name = NULL, *provider_name = NULL;
+       struct lttng_userspace_probe_location *probe_location_local = NULL;
+       struct lttng_userspace_probe_location_lookup_method *lookup_method = NULL;
+
+       assert(opt);
+
+       /*
+        * userspace probe fields are separated by ':'.
+        */
+       tokens = strutils_split(opt, ':', 1);
+       num_token = strutils_array_of_strings_len(tokens);
+
+       /*
+        * Early sanity check that the number of parameter is between 2 and 4
+        * inclusively.
+        * elf:PATH:SYMBOL
+        * std:PATH:PROVIDER_NAME:PROBE_NAME
+        * PATH:SYMBOL (same behavior as ELF)
+        */
+       if (num_token < 2 || num_token > 4) {
+               ret = CMD_ERROR;
+               goto end;
+       }
+
+       /*
+        * Looking up the first parameter will tell the technique to use to
+        * interpret the userspace probe/function description.
+        */
+       switch (num_token) {
+       case 2:
+               /* When the probe type is omitted we assume ELF for now. */
+       case 3:
+               if (num_token == 3 && strcmp(tokens[0], "elf") == 0) {
+                       target_path = tokens[1];
+                       symbol_name = tokens[2];
+               } else if (num_token == 2) {
+                       target_path = tokens[0];
+                       symbol_name = tokens[1];
+               } else {
+                       ret = CMD_ERROR;
+                       goto end;
+               }
+               lookup_method =
+                       lttng_userspace_probe_location_lookup_method_function_elf_create();
+               if (!lookup_method) {
+                       WARN("Failed to create ELF lookup method");
+                       ret = CMD_ERROR;
+                       goto end;
+               }
+               break;
+       case 4:
+               if (strcmp(tokens[0], "sdt") == 0) {
+                       target_path = tokens[1];
+                       provider_name = tokens[2];
+                       probe_name = tokens[3];
+               } else {
+                       ret = CMD_ERROR;
+                       goto end;
+               }
+               lookup_method =
+                       lttng_userspace_probe_location_lookup_method_tracepoint_sdt_create();
+               if (!lookup_method) {
+                       WARN("Failed to create SDT lookup method");
+                       ret = CMD_ERROR;
+                       goto end;
+               }
+               break;
+       default:
+               ret = CMD_ERROR;
+               goto end;
+       }
+
+       /* strutils_unescape_string allocates a new char *. */
+       unescaped_target_path = strutils_unescape_string(target_path, 0);
+       if (!unescaped_target_path) {
+               ret = CMD_ERROR;
+               goto end;
+       }
+
+       /*
+        * If there is not forward slash in the path. Walk the $PATH else
+        * expand.
+        */
+       if (strchr(unescaped_target_path, '/') == NULL) {
+               /* Walk the $PATH variable to find the targeted binary. */
+               real_target_path = zmalloc(LTTNG_PATH_MAX * sizeof(char));
+               if (!real_target_path) {
+                       PERROR("Error allocating path buffer");
+                       ret = CMD_ERROR;
+                       goto end;
+               }
+               ret = walk_command_search_path(unescaped_target_path, real_target_path);
+               if (ret) {
+                       ERR("Binary not found.");
+                       ret = CMD_ERROR;
+                       goto end;
+               }
+       } else {
+               /*
+                * Expand references to `/./` and `/../`. This function does not check
+                * if the file exists. This call returns an allocated buffer on
+                * success.
+                */
+               real_target_path = utils_expand_path_keep_symlink(unescaped_target_path);
+               if (!real_target_path) {
+                       ERR("Error expanding the path to binary.");
+                       ret = CMD_ERROR;
+                       goto end;
+               }
+
+               /*
+                * Check if the file exists using access(2), If it does not,
+                * return an error.
+                */
+               ret = access(real_target_path, F_OK);
+               if (ret) {
+                       ERR("Cannot find binary at path: %s.", real_target_path);
+                       ret = CMD_ERROR;
+                       goto end;
+               }
+       }
+
+       switch (lttng_userspace_probe_location_lookup_method_get_type(lookup_method)) {
+       case LTTNG_USERSPACE_PROBE_LOCATION_LOOKUP_METHOD_TYPE_FUNCTION_ELF:
+               /*
+                * Check for common mistakes in userspace probe description syntax.
+                */
+               ret = warn_userspace_probe_syntax(symbol_name);
+               if (ret) {
+                       goto end;
+               }
+
+               probe_location_local = lttng_userspace_probe_location_function_create(
+                               real_target_path, symbol_name, lookup_method);
+               if (!probe_location_local) {
+                       WARN("Failed to create function probe location");
+                       ret = CMD_ERROR;
+                       goto end;
+               }
+
+               /* Ownership transferred to probe_location. */
+               lookup_method = NULL;
+               break;
+       case LTTNG_USERSPACE_PROBE_LOCATION_LOOKUP_METHOD_TYPE_TRACEPOINT_SDT:
+               probe_location_local = lttng_userspace_probe_location_tracepoint_create(
+                               real_target_path, provider_name, probe_name, lookup_method);
+               if (!probe_location_local) {
+                       WARN("Failed to create function probe location");
+                       ret = CMD_ERROR;
+                       goto end;
+               }
+
+               /* Ownership transferred to probe_location. */
+               lookup_method = NULL;
+               break;
+       default:
+               ret = CMD_ERROR;
+               goto end;
+       }
+
+       /*
+        * Everything went fine, transfer ownership of probe location to
+        * caller.
+        */
+       *probe_location = probe_location_local;
+       probe_location_local = NULL;
+
+end:
+       lttng_userspace_probe_location_destroy(probe_location_local);
+       lttng_userspace_probe_location_lookup_method_destroy(lookup_method);
+       strutils_free_null_terminated_array_of_strings(tokens);
+       /*
+        * Freeing both char * here makes the error handling simplier. free()
+        * performs not action if the pointer is NULL.
+        */
+       free(real_target_path);
+       free(unescaped_target_path);
+
+       return ret;
+}
diff --git a/src/bin/lttng/uprobe.h b/src/bin/lttng/uprobe.h
new file mode 100644 (file)
index 0000000..852f366
--- /dev/null
@@ -0,0 +1,19 @@
+/*
+ * Copyright (C) 2020 EfficiOS, Inc.
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ *
+ */
+
+#ifndef SRC_BIN_LTTNG_UPROBE_H
+#define SRC_BIN_LTTNG_UPROBE_H
+
+#include <common/macros.h>
+
+struct lttng_userspace_probe_location;
+
+LTTNG_HIDDEN
+int parse_userspace_probe_opts(const char *opt,
+               struct lttng_userspace_probe_location **uprobe_loc);
+
+#endif /* SRC_BIN_LTTNG_UPROBE_H */
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