Cleanup: enable_events.c: fix erroneous comment

[lttng-tools.git] / src / bin / lttng / commands / enable_events.c

diff --git a/src/bin/lttng/commands/enable_events.c b/src/bin/lttng/commands/enable_events.c
index 23dff2038f3ef17b1090ba63e186771f9ee5d60a..3d32cbf813bc2615b211888748018fbebb77b5d8 100644 (file)
--- a/src/bin/lttng/commands/enable_events.c
+++ b/src/bin/lttng/commands/enable_events.c
@@ -290,6 +290,65 @@ 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
@@ -389,7 +448,7 @@ static int parse_userspace_probe_opts(struct lttng_event *ev, char *opt)
        /* strutils_unescape_string allocates a new char *. */
        unescaped_target_path = strutils_unescape_string(target_path, 0);
        if (!unescaped_target_path) {
-               ret = -LTTNG_ERR_INVALID;
+               ret = CMD_ERROR;
                goto end_destroy_lookup_method;
        }
 
@@ -425,11 +484,12 @@ static int parse_userspace_probe_opts(struct lttng_event *ev, char *opt)
                }
 
                /*
-                * Check if the file exists using access(2). If it does not, walk the
-                * $PATH.
+                * 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;
                }
@@ -437,6 +497,14 @@ static int parse_userspace_probe_opts(struct lttng_event *ev, char *opt)
 
        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) {
@@ -737,7 +805,7 @@ char *print_exclusions(char **names)
 {
        int length = 0;
        int i;
-       const char *preamble = " excluding ";
+       const char preamble[] = " excluding ";
        char *ret;
        int count = names ? strutils_array_of_strings_len(names) : 0;
 
@@ -750,9 +818,8 @@ char *print_exclusions(char **names)
                length += strlen(names[i]) + 4;
        }
 
-       /* add length of preamble + one for NUL - one for last (missing) comma */
-       length += strlen(preamble);
-       ret = zmalloc(length + 1);
+       length += sizeof(preamble);
+       ret = zmalloc(length);
        if (!ret) {
                return NULL;
        }
@@ -1296,8 +1363,19 @@ static int enable_events(char *session_name)
                        case LTTNG_EVENT_USERSPACE_PROBE:
                                ret = parse_userspace_probe_opts(ev, opt_userspace_probe);
                                if (ret) {
-                                       ERR("Unable to parse userspace probe options");
-                                       ret = CMD_ERROR;
+                                       switch (ret) {
+                                       case CMD_UNSUPPORTED:
+                                               /*
+                                                * Error message describing
+                                                * what is not supported was
+                                                * printed in the function.
+                                                */
+                                               break;
+                                       case CMD_ERROR:
+                                       default:
+                                               ERR("Unable to parse userspace probe options");
+                                               break;
+                                       }
                                        goto error;
                                }
                                break;