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Subject[PATCH 2/6 v3] tools lib fs: Add helper to find mounted file systems
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

In preparation for adding tracefs for perf to use, create a findfs
helper utility that find_debugfs uses instead of hard coding the search
in the code. This will allow for a find_tracefs to be used as well.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
tools/lib/api/Makefile | 2 ++
tools/lib/api/fs/debugfs.c | 51 ++++++-------------------------------
tools/lib/api/fs/debugfs.h | 11 +-------
tools/lib/api/fs/findfs.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++
tools/lib/api/fs/findfs.h | 21 ++++++++++++++++
5 files changed, 94 insertions(+), 54 deletions(-)
create mode 100644 tools/lib/api/fs/findfs.c
create mode 100644 tools/lib/api/fs/findfs.h

diff --git a/tools/lib/api/Makefile b/tools/lib/api/Makefile
index 36c08b1f4afb..22b2f15d7255 100644
--- a/tools/lib/api/Makefile
+++ b/tools/lib/api/Makefile
@@ -9,11 +9,13 @@ LIB_H=
LIB_OBJS=

LIB_H += fs/debugfs.h
+LIB_H += fs/findfs.h
LIB_H += fs/fs.h
# See comment below about piggybacking...
LIB_H += fd/array.h

LIB_OBJS += $(OUTPUT)fs/debugfs.o
+LIB_OBJS += $(OUTPUT)fs/findfs.o
LIB_OBJS += $(OUTPUT)fs/fs.o
# XXX piggybacking here, need to introduce libapikfd, or rename this
# to plain libapik.a and make it have it all api goodies
diff --git a/tools/lib/api/fs/debugfs.c b/tools/lib/api/fs/debugfs.c
index d21d4d6b4fd2..91e1668348ce 100644
--- a/tools/lib/api/fs/debugfs.c
+++ b/tools/lib/api/fs/debugfs.c
@@ -20,58 +20,21 @@ static const char * const debugfs_known_mountpoints[] = {

static bool debugfs_found;

-/* verify that a mountpoint is actually a debugfs instance */
-
-static int debugfs_valid_mountpoint(const char *debugfs)
-{
- struct statfs st_fs;
-
- if (statfs(debugfs, &st_fs) < 0)
- return -ENOENT;
- else if ((long)st_fs.f_type != (long)DEBUGFS_MAGIC)
- return -ENOENT;
-
- return 0;
-}
-
/* find the path to the mounted debugfs */
const char *debugfs_find_mountpoint(void)
{
- const char * const *ptr;
- char type[100];
- FILE *fp;
+ const char *ret;

if (debugfs_found)
return (const char *)debugfs_mountpoint;

- ptr = debugfs_known_mountpoints;
- while (*ptr) {
- if (debugfs_valid_mountpoint(*ptr) == 0) {
- debugfs_found = true;
- strcpy(debugfs_mountpoint, *ptr);
- return debugfs_mountpoint;
- }
- ptr++;
- }
+ ret = find_mountpoint("debugfs", (long) DEBUGFS_MAGIC,
+ debugfs_mountpoint, PATH_MAX + 1,
+ debugfs_known_mountpoints);
+ if (ret)
+ debugfs_found = true;

- /* give up and parse /proc/mounts */
- fp = fopen("/proc/mounts", "r");
- if (fp == NULL)
- return NULL;
-
- while (fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
- debugfs_mountpoint, type) == 2) {
- if (strcmp(type, "debugfs") == 0)
- break;
- }
- fclose(fp);
-
- if (strcmp(type, "debugfs") != 0)
- return NULL;
-
- debugfs_found = true;
-
- return debugfs_mountpoint;
+ return ret;
}

/* mount the debugfs somewhere if it's not mounted */
diff --git a/tools/lib/api/fs/debugfs.h b/tools/lib/api/fs/debugfs.h
index 77bb36a95b07..1074ac81358e 100644
--- a/tools/lib/api/fs/debugfs.h
+++ b/tools/lib/api/fs/debugfs.h
@@ -1,16 +1,7 @@
#ifndef __API_DEBUGFS_H__
#define __API_DEBUGFS_H__

-#define _STR(x) #x
-#define STR(x) _STR(x)
-
-/*
- * On most systems <limits.h> would have given us this, but not on some systems
- * (e.g. GNU/Hurd).
- */
-#ifndef PATH_MAX
-#define PATH_MAX 4096
-#endif
+#include "findfs.h"

#ifndef DEBUGFS_MAGIC
#define DEBUGFS_MAGIC 0x64626720
diff --git a/tools/lib/api/fs/findfs.c b/tools/lib/api/fs/findfs.c
new file mode 100644
index 000000000000..49946cb6d7af
--- /dev/null
+++ b/tools/lib/api/fs/findfs.c
@@ -0,0 +1,63 @@
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+#include <sys/vfs.h>
+
+#include "findfs.h"
+
+/* verify that a mountpoint is actually the type we want */
+
+int valid_mountpoint(const char *mount, long magic)
+{
+ struct statfs st_fs;
+
+ if (statfs(mount, &st_fs) < 0)
+ return -ENOENT;
+ else if ((long)st_fs.f_type != magic)
+ return -ENOENT;
+
+ return 0;
+}
+
+/* find the path to a mounted file system */
+const char *find_mountpoint(const char *fstype, long magic,
+ char *mountpoint, int len,
+ const char * const *known_mountpoints)
+{
+ const char * const *ptr;
+ char format[128];
+ char type[100];
+ FILE *fp;
+
+ if (known_mountpoints) {
+ ptr = known_mountpoints;
+ while (*ptr) {
+ if (valid_mountpoint(*ptr, magic) == 0) {
+ strncpy(mountpoint, *ptr, len - 1);
+ mountpoint[len-1] = 0;
+ return mountpoint;
+ }
+ ptr++;
+ }
+ }
+
+ /* give up and parse /proc/mounts */
+ fp = fopen("/proc/mounts", "r");
+ if (fp == NULL)
+ return NULL;
+
+ snprintf(format, 128, "%%*s %%%ds %%99s %%*s %%*d %%*d\n", len);
+
+ while (fscanf(fp, format, mountpoint, type) == 2) {
+ if (strcmp(type, fstype) == 0)
+ break;
+ }
+ fclose(fp);
+
+ if (strcmp(type, fstype) != 0)
+ return NULL;
+
+ return mountpoint;
+}
diff --git a/tools/lib/api/fs/findfs.h b/tools/lib/api/fs/findfs.h
new file mode 100644
index 000000000000..9e7d876791e1
--- /dev/null
+++ b/tools/lib/api/fs/findfs.h
@@ -0,0 +1,21 @@
+#ifndef __API_FINDFS_H__
+#define __API_FINDFS_H__
+
+#define _STR(x) #x
+#define STR(x) _STR(x)
+
+/*
+ * On most systems <limits.h> would have given us this, but not on some systems
+ * (e.g. GNU/Hurd).
+ */
+#ifndef PATH_MAX
+#define PATH_MAX 4096
+#endif
+
+const char *find_mountpoint(const char *fstype, long magic,
+ char *mountpoint, int len,
+ const char * const *known_mountpoints);
+
+int valid_mountpoint(const char *mount, long magic);
+
+#endif /* __API_FINDFS_H__ */
--
2.1.4



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