Introduce a new utils_resolve_relative function
[lttng-tools.git] / src / common / utils.c
index b345100ea0fa5ad6517d28c72cbc53a5bd87e391..4ccf36a6c781bc09bbcb6a1108af8354d275e9b6 100644 (file)
@@ -27,6 +27,7 @@
 #include <unistd.h>
 #include <inttypes.h>
 #include <regex.h>
+#include <grp.h>
 
 #include <common/common.h>
 #include <common/runas.h>
 #include "utils.h"
 #include "defaults.h"
 
+/*
+ * Resolve the './' and '../' strings in the middle of a path using
+ * our very own way to do it, so that it works even if the directory
+ * does not exist
+ */
+LTTNG_HIDDEN
+char *utils_resolve_relative(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;
+       }
+
+       /* Copy the path in the absolute path */
+       strncpy(absolute_path, path, PATH_MAX);
+
+       /* As long as we find '/./' in the 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 path string */
+       while ((next = strstr(absolute_path, "/../"))) {
+               /* If the path starts with '/../', there's a problem */
+               if (next == absolute_path) {
+                       ERR("%s: Path cannot be resolved", path);
+                       goto error;
+               }
+
+               /* We find the last level of directory */
+               previous = absolute_path;
+               while ((slash = strpbrk(previous + 1, "/")) && slash != next) {
+                       previous = slash;
+               }
+
+               /* 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 + 3);
+
+               free(start_path);
+       }
+
+       return absolute_path;
+
+error:
+       free(absolute_path);
+       return NULL;
+}
+
+
 /*
  * 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
@@ -351,10 +420,11 @@ error:
  */
 LTTNG_HIDDEN
 int utils_create_stream_file(const char *path_name, char *file_name, uint64_t size,
-               uint64_t count, int uid, int gid)
+               uint64_t count, int uid, int gid, char *suffix)
 {
        int ret, out_fd, flags, mode;
-       char full_path[PATH_MAX], *path_name_id = NULL, *path;
+       char full_path[PATH_MAX], *path_name_suffix = NULL, *path;
+       char *extra = NULL;
 
        assert(path_name);
        assert(file_name);
@@ -366,17 +436,30 @@ int utils_create_stream_file(const char *path_name, char *file_name, uint64_t si
                goto error;
        }
 
+       /* Setup extra string if suffix or/and a count is needed. */
+       if (size > 0 && suffix) {
+               ret = asprintf(&extra, "_%" PRIu64 "%s", count, suffix);
+       } else if (size > 0) {
+               ret = asprintf(&extra, "_%" PRIu64, count);
+       } else if (suffix) {
+               ret = asprintf(&extra, "%s", suffix);
+       }
+       if (ret < 0) {
+               PERROR("Allocating extra string to name");
+               goto error;
+       }
+
        /*
         * If we split the trace in multiple files, we have to add the count at the
         * end of the tracefile name
         */
-       if (size > 0) {
-               ret = asprintf(&path_name_id, "%s_%" PRIu64, full_path, count);
+       if (extra) {
+               ret = asprintf(&path_name_suffix, "%s%s", full_path, extra);
                if (ret < 0) {
-                       PERROR("Allocating path name ID");
-                       goto error;
+                       PERROR("Allocating path name with extra string");
+                       goto error_free_suffix;
                }
-               path = path_name_id;
+               path = path_name_suffix;
        } else {
                path = full_path;
        }
@@ -397,7 +480,9 @@ int utils_create_stream_file(const char *path_name, char *file_name, uint64_t si
        ret = out_fd;
 
 error_open:
-       free(path_name_id);
+       free(path_name_suffix);
+error_free_suffix:
+       free(extra);
 error:
        return ret;
 }
@@ -413,10 +498,14 @@ error:
  */
 LTTNG_HIDDEN
 int utils_rotate_stream_file(char *path_name, char *file_name, uint64_t size,
-               uint64_t count, int uid, int gid, int out_fd, uint64_t *new_count)
+               uint64_t count, int uid, int gid, int out_fd, uint64_t *new_count,
+               int *stream_fd)
 {
        int ret;
 
+       assert(new_count);
+       assert(stream_fd);
+
        ret = close(out_fd);
        if (ret < 0) {
                PERROR("Closing tracefile");
@@ -429,8 +518,16 @@ int utils_rotate_stream_file(char *path_name, char *file_name, uint64_t size,
                (*new_count)++;
        }
 
-       return utils_create_stream_file(path_name, file_name, size, *new_count,
-                       uid, gid);
+       ret = utils_create_stream_file(path_name, file_name, size, *new_count,
+                       uid, gid, 0);
+       if (ret < 0) {
+               goto error;
+       }
+       *stream_fd = ret;
+
+       /* Success. */
+       ret = 0;
+
 error:
        return ret;
 }
@@ -666,3 +763,24 @@ 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;
+}
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