[PATCH 1/2] fw_env: make flash_io() take buffer as an argument

Rafał Miłecki
2022-01-11T02:00:53Z

It's usually easier to understand code & follow it if all arguments are
passed explicitly. Many coding styles also discourage using global
variables.

Behaviour of flash_io() was a bit unintuitive as it was writing to a
buffer referenced in a global struct. That required developers to
remember how it works and sometimes required hacking "environment"
global struct variable to read data into a proper buffer.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
tools/env/fw_env.c | 32 ++++++++++++++++----------------
1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/tools/env/fw_env.c b/tools/env/fw_env.c
index 3da75be783..f90293d7ce 100644
--- a/tools/env/fw_env.c
+++ b/tools/env/fw_env.c
@@ -346,7 +346,7 @@ static int ubi_write(int fd, const void *buf, size_t count)
return 0;
}

-static int flash_io(int mode);
+static int flash_io(int mode, void *buf, size_t count);
static int parse_config(struct env_opts *opts);

#if defined(CONFIG_FILE)
@@ -516,7 +516,7 @@ int fw_env_flush(struct env_opts *opts)
*environment.crc = crc32(0, (uint8_t *) environment.data, ENV_SIZE);

/* write environment back to flash */
- if (flash_io(O_RDWR)) {
+ if (flash_io(O_RDWR, environment.data, ENV_SIZE)) {
fprintf(stderr, "Error: can't write fw_env to flash\n");
return -1;
}
@@ -1185,7 +1185,8 @@ static int flash_flag_obsolete(int dev, int fd, off_t offset)
return rc;
}

-static int flash_write(int fd_current, int fd_target, int dev_target)
+static int flash_write(int fd_current, int fd_target, int dev_target, void *buf,
+ size_t count)
{
int rc;

@@ -1212,11 +1213,10 @@ static int flash_write(int fd_current, int fd_target, int dev_target)
if (IS_UBI(dev_target)) {
if (ubi_update_start(fd_target, CUR_ENVSIZE) < 0)
return -1;
- return ubi_write(fd_target, environment.image, CUR_ENVSIZE);
+ return ubi_write(fd_target, buf, count);
}

- rc = flash_write_buf(dev_target, fd_target, environment.image,
- CUR_ENVSIZE);
+ rc = flash_write_buf(dev_target, fd_target, buf, count);
if (rc < 0)
return rc;

@@ -1235,17 +1235,17 @@ static int flash_write(int fd_current, int fd_target, int dev_target)
return 0;
}

-static int flash_read(int fd)
+static int flash_read(int fd, void *buf, size_t count)
{
int rc;

if (IS_UBI(dev_current)) {
DEVTYPE(dev_current) = MTD_ABSENT;

- return ubi_read(fd, environment.image, CUR_ENVSIZE);
+ return ubi_read(fd, buf, count);
}

- rc = flash_read_buf(dev_current, fd, environment.image, CUR_ENVSIZE,
+ rc = flash_read_buf(dev_current, fd, buf, count,
DEVOFFSET(dev_current));
if (rc != CUR_ENVSIZE)
return -1;
@@ -1291,7 +1291,7 @@ err:
return rc;
}

-static int flash_io_write(int fd_current)
+static int flash_io_write(int fd_current, void *buf, size_t count)
{
int fd_target = -1, rc, dev_target;
const char *dname, *target_temp = NULL;
@@ -1322,7 +1322,7 @@ static int flash_io_write(int fd_current)
fd_target = fd_current;
}

- rc = flash_write(fd_current, fd_target, dev_target);
+ rc = flash_write(fd_current, fd_target, dev_target, buf, count);

if (fsync(fd_current) && !(errno == EINVAL || errno == EROFS)) {
fprintf(stderr,
@@ -1377,7 +1377,7 @@ static int flash_io_write(int fd_current)
return rc;
}

-static int flash_io(int mode)
+static int flash_io(int mode, void *buf, size_t count)
{
int fd_current, rc;

@@ -1391,9 +1391,9 @@ static int flash_io(int mode)
}

if (mode == O_RDWR) {
- rc = flash_io_write(fd_current);
+ rc = flash_io_write(fd_current, buf, count);
} else {
- rc = flash_read(fd_current);
+ rc = flash_read(fd_current, buf, count);
}

if (close(fd_current)) {
@@ -1455,7 +1455,7 @@ int fw_env_open(struct env_opts *opts)
}

dev_current = 0;
- if (flash_io(O_RDONLY)) {
+ if (flash_io(O_RDONLY, environment.data, CUR_ENVSIZE)) {
ret = -EIO;
goto open_cleanup;
}
@@ -1490,7 +1490,7 @@ int fw_env_open(struct env_opts *opts)
* other pointers in environment still point inside addr0
*/
environment.image = addr1;
- if (flash_io(O_RDONLY)) {
+ if (flash_io(O_RDONLY, environment.data, CUR_ENVSIZE)) {
ret = -EIO;
goto open_cleanup;
}
--
2.31.1