X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fcommon%2Futils.c;h=3a4f850ba66b22f19d78bdbd9dd52e1257d8ba75;hp=dd9967312aca1be20253df8fd881c485858d0e6f;hb=664958450af7685c38cccfc9109d8f5b050e0fd9;hpb=309167d2a6f59d0c8cbf64eb23ba912cdea76a34 diff --git a/src/common/utils.c b/src/common/utils.c index dd9967312..3a4f850ba 100644 --- a/src/common/utils.c +++ b/src/common/utils.c @@ -1,5 +1,6 @@ /* * Copyright (C) 2012 - David Goulet + * Copyright (C) 2013 - Raphaël Beamonte * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License, version 2 only, as @@ -27,6 +28,7 @@ #include #include #include +#include #include #include @@ -35,58 +37,214 @@ #include "defaults.h" /* - * Return the realpath(3) of the path even if the last directory token does not - * exist. For example, with /tmp/test1/test2, if test2/ does not exist but the - * /tmp/test1 does, the real path is returned. In normal time, realpath(3) - * fails if the end point directory does not exist. + * Return a partial realpath(3) of the path even if the full path does not + * exist. For instance, with /tmp/test1/test2/test3, if test2/ does not exist + * but the /tmp/test1 does, the real path for /tmp/test1 is concatened with + * /test2/test3 then returned. In normal time, realpath(3) fails if the end + * point directory does not exist. + * In case resolved_path is NULL, the string returned was allocated in the + * function and thus need to be freed by the caller. The size argument allows + * to specify the size of the resolved_path argument if given, or the size to + * allocate. */ LTTNG_HIDDEN -char *utils_expand_path(const char *path) +char *utils_partial_realpath(const char *path, char *resolved_path, size_t size) { - const char *end_path = path; - char *next, *cut_path = NULL, *expanded_path = NULL; + char *cut_path, *try_path = NULL, *try_path_prev = NULL; + const char *next, *prev, *end; /* Safety net */ if (path == NULL) { goto error; } - /* Find last token delimited by '/' */ - while ((next = strpbrk(end_path + 1, "/"))) { - end_path = next; + /* + * Identify the end of the path, we don't want to treat the + * last char if it is a '/', we will just keep it on the side + * to be added at the end, and return a value coherent with + * the path given as argument + */ + end = path + strlen(path); + if (*(end-1) == '/') { + end--; } - /* Cut last token from original path */ - cut_path = strndup(path, end_path - path); + /* Initiate the values of the pointers before looping */ + next = path; + prev = next; + /* Only to ensure try_path is not NULL to enter the while */ + try_path = (char *)next; - expanded_path = zmalloc(PATH_MAX); - if (expanded_path == NULL) { - PERROR("zmalloc expand path"); - goto error; + /* Resolve the canonical path of the first part of the path */ + while (try_path != NULL && next != end) { + /* + * If there is not any '/' left, we want to try with + * the full path + */ + next = strpbrk(next + 1, "/"); + if (next == NULL) { + next = end; + } + + /* Cut the part we will be trying to resolve */ + cut_path = strndup(path, next - path); + + /* Try to resolve this part */ + try_path = realpath((char *)cut_path, NULL); + if (try_path == NULL) { + /* + * There was an error, we just want to be assured it + * is linked to an unexistent directory, if it's another + * reason, we spawn an error + */ + switch (errno) { + case ENOENT: + /* Ignore the error */ + break; + default: + PERROR("realpath (partial_realpath)"); + goto error; + break; + } + } else { + /* Save the place we are before trying the next step */ + free(try_path_prev); + try_path_prev = try_path; + prev = next; + } + + /* Free the allocated memory */ + free(cut_path); + }; + + /* Allocate memory for the resolved path if necessary */ + if (resolved_path == NULL) { + resolved_path = zmalloc(size); + if (resolved_path == NULL) { + PERROR("zmalloc resolved path"); + goto error; + } } - expanded_path = realpath((char *)cut_path, expanded_path); - if (expanded_path == NULL) { - switch (errno) { - case ENOENT: - ERR("%s: No such file or directory", cut_path); - break; - default: - PERROR("realpath utils expand path"); - break; + /* + * If we were able to solve at least partially the path, we can concatenate + * what worked and what didn't work + */ + if (try_path_prev != NULL) { + /* If we risk to concatenate two '/', we remove one of them */ + if (try_path_prev[strlen(try_path_prev) - 1] == '/' && prev[0] == '/') { + try_path_prev[strlen(try_path_prev) - 1] = '\0'; } + + /* + * Duplicate the memory used by prev in case resolved_path and + * path are pointers for the same memory space + */ + cut_path = strdup(prev); + + /* Concatenate the strings */ + snprintf(resolved_path, size, "%s%s", try_path_prev, cut_path); + + /* Free the allocated memory */ + free(cut_path); + free(try_path_prev); + /* + * Else, we just copy the path in our resolved_path to + * return it as is + */ + } else { + strncpy(resolved_path, path, size); + } + + /* Then we return the 'partially' resolved path */ + return resolved_path; + +error: + free(resolved_path); + return NULL; +} + +/* + * Make a full resolution of the given path even if it doesn't exist. + * This function uses the utils_partial_realpath function to resolve + * symlinks and relatives paths at the start of the string, and + * implements functionnalities to resolve the './' and '../' strings + * in the middle of a path. This function is only necessary because + * realpath(3) does not accept to resolve unexistent paths. + * The returned string was allocated in the function, it is thus of + * the responsibility of the caller to free this memory. + */ +LTTNG_HIDDEN +char *utils_expand_path(const char *path) +{ + char *next, *previous, *slash, *start_path, *absolute_path = NULL; + + /* Safety net */ + if (path == NULL) { + goto error; + } + + /* Allocate memory for the absolute_path */ + absolute_path = zmalloc(PATH_MAX); + if (absolute_path == NULL) { + PERROR("zmalloc expand path"); goto error; } - /* Add end part to expanded path */ - strncat(expanded_path, end_path, PATH_MAX - strlen(expanded_path) - 1); + /* + * If the path is not already absolute nor explicitly relative, + * consider we're in the current directory + */ + if (*path != '/' && strncmp(path, "./", 2) != 0 && + strncmp(path, "../", 3) != 0) { + snprintf(absolute_path, PATH_MAX, "./%s", path); + /* Else, we just copy the path */ + } else { + strncpy(absolute_path, path, PATH_MAX); + } + + /* Resolve partially our path */ + absolute_path = utils_partial_realpath(absolute_path, + absolute_path, PATH_MAX); + + /* As long as we find '/./' in the working_path string */ + while ((next = strstr(absolute_path, "/./"))) { + + /* We prepare the start_path not containing it */ + start_path = strndup(absolute_path, next - absolute_path); + + /* And we concatenate it with the part after this string */ + snprintf(absolute_path, PATH_MAX, "%s%s", start_path, next + 2); + + free(start_path); + } + + /* As long as we find '/../' in the working_path string */ + while ((next = strstr(absolute_path, "/../"))) { + /* We find the last level of directory */ + previous = absolute_path; + while ((slash = strpbrk(previous, "/")) && slash != next) { + previous = slash + 1; + } + + /* Then we prepare the start_path not containing it */ + start_path = strndup(absolute_path, previous - absolute_path); + + /* And we concatenate it with the part after the '/../' */ + snprintf(absolute_path, PATH_MAX, "%s%s", start_path, next + 4); - free(cut_path); - return expanded_path; + /* We can free the memory used for the start path*/ + free(start_path); + + /* Then we verify for symlinks using partial_realpath */ + absolute_path = utils_partial_realpath(absolute_path, + absolute_path, PATH_MAX); + } + + return absolute_path; error: - free(expanded_path); - free(cut_path); + free(absolute_path); return NULL; } @@ -694,3 +852,24 @@ size_t utils_get_current_time_str(const char *format, char *dst, size_t len) return ret; } + +/* + * Return the group ID matching name, else 0 if it cannot be found. + */ +LTTNG_HIDDEN +gid_t utils_get_group_id(const char *name) +{ + struct group *grp; + + grp = getgrnam(name); + if (!grp) { + static volatile int warn_once; + + if (!warn_once) { + WARN("No tracing group detected"); + warn_once = 1; + } + return 0; + } + return grp->gr_gid; +}