From 7c2b882ed11639736070beb97d5748942813742a Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" Date: Mon, 14 Nov 2022 15:45:22 -0500 Subject: libtracefs: Add tracefs_tracing_dir_is_mounted() API Add the tracefs_tracing_dir_is_mounted() API that passes in a mount flag and an address to a char pointer (or NULL). It returns 1 if the tracing_dir was already mounted and 0 if not. If the mount flag is set, then it will try to mount it and return -1 if it fails. If path points to the address of a char*, then it will be set to the path that was mounted, or was already mounted. This is useful for wanting to unmount the tracing_dir if the tool was the one that mounted it. Link: https://lore.kernel.org/linux-trace-devel/20221114204522.2433500-5-rostedt@goodmis.org Signed-off-by: Steven Rostedt (Google) --- Documentation/libtracefs-files.txt | 14 +++++++-- Documentation/libtracefs.txt | 1 + include/tracefs.h | 1 + src/tracefs-utils.c | 62 ++++++++++++++++++++++++++++++-------- 4 files changed, 64 insertions(+), 14 deletions(-) diff --git a/Documentation/libtracefs-files.txt b/Documentation/libtracefs-files.txt index 2a3f544..d22e759 100644 --- a/Documentation/libtracefs-files.txt +++ b/Documentation/libtracefs-files.txt @@ -3,8 +3,8 @@ libtracefs(3) NAME ---- -tracefs_get_tracing_file, tracefs_put_tracing_file, tracefs_tracing_dir, tracefs_debug_dir, tracefs_set_tracing_dir - -Find and set locations of trace directory and files. +tracefs_get_tracing_file, tracefs_put_tracing_file, tracefs_tracing_dir, tracefs_debug_dir, tracefs_set_tracing_dir, +tracefs_tracing_dir_is_mounted - Find and set locations of trace directory and files. SYNOPSIS -------- @@ -17,6 +17,7 @@ void *tracefs_put_tracing_file*(char pass:[*]_name_); const char pass:[*]*tracefs_tracing_dir*(void); const char pass:[*]*tracefs_debug_dir*(void); int *tracefs_set_tracing_dir*(char pass:[*]_tracing_dir_) +int *tracefs_tracing_dir_is_mounted*(bool _mount_, const char pass:[**]_path_); -- DESCRIPTION @@ -52,6 +53,12 @@ that it will return where the debugfs file system is mounted. If it is not mounted it will try to mount it. The return string must _not_ be freed. +*tracefs_tracing_dir_is_mounted()* returns 1 if the tracing directory is +already mounted and 0 if it is not. If _mount_ is true, it will try to +mount it if it is not, and returns 0 if it succesfully mounted it and -1 +if it did not. If _path_ is set, it will be assigned to the path where it +mounted it. _path_ is internal and should not be freed. + RETURN VALUE ------------ The *tracefs_set_tracing_dir()* function returns 0 on success, -1 otherwise. @@ -65,6 +72,9 @@ in case of an error. The returned string must _not_ be freed. The *tracefs_debug_dir()* function returns a constant string or NULL in case of an error. The returned string must _not_ be freed. +The *tracefs_tracing_dir_is_mounted()* returns 1 if the tracing directory +is already mounted, 0 if it is not, and -1 on error. + EXAMPLE ------- [source,c] diff --git a/Documentation/libtracefs.txt b/Documentation/libtracefs.txt index 73c4997..cc53388 100644 --- a/Documentation/libtracefs.txt +++ b/Documentation/libtracefs.txt @@ -17,6 +17,7 @@ Locations of tracing files and directories: const char pass:[*]*tracefs_tracing_dir*(void); const char pass:[*]*tracefs_debug_dir*(void); int *tracefs_set_tracing_dir*(char pass:[*]_tracing_dir_) + int *tracefs_tracing_dir_is_mounted*(bool _mount_, const char pass:[**]_path_); Trace instances: struct tracefs_instance pass:[*]*tracefs_instance_create*(const char pass:[*]_name_); diff --git a/include/tracefs.h b/include/tracefs.h index 5ff0c6f..10f84a2 100644 --- a/include/tracefs.h +++ b/include/tracefs.h @@ -17,6 +17,7 @@ void tracefs_put_tracing_file(char *name); const char *tracefs_tracing_dir(void); const char *tracefs_debug_dir(void); int tracefs_set_tracing_dir(char *tracing_dir); +int tracefs_tracing_dir_is_mounted(bool mount, const char **path); /* ftrace instances */ struct tracefs_instance; diff --git a/src/tracefs-utils.c b/src/tracefs-utils.c index a38da66..777912e 100644 --- a/src/tracefs-utils.c +++ b/src/tracefs-utils.c @@ -85,14 +85,7 @@ static int mount_debugfs(void) return ret; } -/** - * trace_find_tracing_dir - Find tracing directory - * @debugfs: Boolean to just return the debugfs directory - * - * Returns string containing the full path to the system's tracing directory. - * The string must be freed by free() - */ -__hidden char *trace_find_tracing_dir(bool debugfs) +static char *find_tracing_dir(bool debugfs, bool mount) { char *debug_str = NULL; char fspath[PATH_MAX+1]; @@ -127,18 +120,19 @@ __hidden char *trace_find_tracing_dir(bool debugfs) if (debugfs) { if (strcmp(type, "debugfs") != 0) { - if (mount_debugfs() < 0) + if (!mount || mount_debugfs() < 0) return NULL; strcpy(fspath, DEBUGFS_PATH); } } else if (strcmp(type, "tracefs") != 0) { - if (mount_tracefs() < 0) { + if (!mount || mount_tracefs() < 0) { if (debug_str) { strncpy(fspath, debug_str, PATH_MAX); fspath[PATH_MAX] = 0; } else { - if (mount_debugfs() < 0) { - tracefs_warning("debugfs not mounted, please mount"); + if (!mount || mount_debugfs() < 0) { + if (mount) + tracefs_warning("debugfs not mounted, please mount"); free(debug_str); return NULL; } @@ -165,6 +159,50 @@ __hidden char *trace_find_tracing_dir(bool debugfs) return tracing_dir; } +/** + * tracefs_tracing_dir_is_mounted - test if the tracing dir is already mounted + * @mount: Mount it if it is not already mounted + * @path: the path to the tracing directory if mounted or was mounted + * + * Returns 1 if the tracing directory is already mounted and 0 if it is not. + * If @mount is set and it fails to mount, it returns -1. + * + * If path is not NULL, and the tracing directory is or was mounted, it holds + * the path to the tracing directory. It must not be freed. + */ +int tracefs_tracing_dir_is_mounted(bool mount, const char **path) +{ + const char *dir; + + dir = find_tracing_dir(false, false); + if (dir) { + if (path) + *path = dir; + return 1; + } + if (!mount) + return 0; + + dir = find_tracing_dir(false, mount); + if (!dir) + return -1; + if (path) + *path = dir; + return 0; +} + +/** + * trace_find_tracing_dir - Find tracing directory + * @debugfs: Boolean to just return the debugfs directory + * + * Returns string containing the full path to the system's tracing directory. + * The string must be freed by free() + */ +__hidden char *trace_find_tracing_dir(bool debugfs) +{ + return find_tracing_dir(debugfs, false); +} + /** * tracefs_set_tracing_dir - Set location of the tracing directory * @tracing_dir: full path to the system's tracing directory mount point. -- cgit 1.2.3-korg