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btrfs-progs: add write helpers for sysfs files 

Add convenience wrappers for writing a buffer or u64 to toplevel or FSID
file in sysfs.

Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2023-12-08 22:43:59 +01:00
parent b3b38751e9
commit 4576029dfd
2 changed files with 66 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

65
common/sysfs-utils.c
View File

@ -26,7 +26,7 @@
* Open a file in fsid directory in sysfs and return the file descriptor or
* error
*/
int sysfs_open_fsid_file(int fd, const char *filename)
static int sysfs_open_fsid_file_flags(int fd, const char *filename, int flags)
{
u8 fsid[BTRFS_UUID_SIZE];
char fsid_str[BTRFS_UUID_UNPARSED_SIZE];
@ -42,14 +42,24 @@ int sysfs_open_fsid_file(int fd, const char *filename)
if (ret < 0)
return ret;
return open(sysfs_file, O_RDONLY);
return open(sysfs_file, flags);
}
int sysfs_open_fsid_file(int fd, const char *filename)
{
return sysfs_open_fsid_file_flags(fd, filename, O_RDONLY);
}
int sysfs_open_fsid_file_rw(int fd, const char *filename)
{
return sysfs_open_fsid_file_flags(fd, filename, O_RDWR);
}
/*
* Open a file in the toplevel sysfs directory and return the file descriptor
* or error.
*/
int sysfs_open_file(const char *name)
static int sysfs_open_file_flags(const char *name, int flags)
{
char path[PATH_MAX];
int ret;
@ -57,7 +67,17 @@ int sysfs_open_file(const char *name)
ret = path_cat_out(path, "/sys/fs/btrfs", name);
if (ret < 0)
return ret;
return open(path, O_RDONLY);
return open(path, flags);
}
int sysfs_open_file(const char *name)
{
return sysfs_open_file_flags(name, O_RDONLY);
}
int sysfs_open_file_rw(const char *name)
{
return sysfs_open_file_flags(name, O_RDWR);
}
/*
@ -94,6 +114,12 @@ int sysfs_read_file(int fd, char *buf, size_t size)
return read(fd, buf, size);
}
int sysfs_write_file(int fd, const char *buf, size_t size)
{
lseek(fd, 0, SEEK_SET);
return write(fd, buf, size);
}
int sysfs_read_file_u64(const char *name, u64 *value)
{
int fd = -1;
@ -115,6 +141,22 @@ out:
return ret;
}
int sysfs_write_file_u64(const char *name, u64 value)
{
int fd;
int ret;
char str[32] = { 0 };
fd = sysfs_open_file_rw(name);
if (fd < 0)
return fd;
ret = snprintf(str, sizeof(str), "%llu", value);
ret = sysfs_write_file(fd, str, ret);
close(fd);
return ret;
}
int sysfs_read_fsid_file_u64(int fd, const char *name, u64 *value)
{
int ret;
@ -134,3 +176,18 @@ out:
close(fd);
return ret;
}
int sysfs_write_fsid_file_u64(int fd, const char *name, u64 value)
{
int ret;
char str[32] = { 0 };
fd = sysfs_open_fsid_file_rw(fd, name);
if (fd < 0)
return fd;
ret = snprintf(str, sizeof(str), "%llu", value);
ret = sysfs_write_file(fd, str, ret);
close(fd);
return ret;
}

5
common/sysfs-utils.h
View File

@ -20,10 +20,15 @@
#include <stddef.h>
int sysfs_open_file(const char *name);
int sysfs_open_file_rw(const char *name);
int sysfs_open_fsid_file(int fd, const char *filename);
int sysfs_open_fsid_file_rw(int fd, const char *filename);
int sysfs_open_fsid_dir(int fd, const char *dirname);
int sysfs_read_fsid_file_u64(int fd, const char *name, u64 *value);
int sysfs_write_fsid_file_u64(int fd, const char *name, u64 value);
int sysfs_read_file(int fd, char *buf, size_t size);
int sysfs_write_file(int fd, const char *buf, size_t size);
int sysfs_read_file_u64(const char *name, u64 *value);
int sysfs_write_file_u64(const char *name, u64 value);
#endif