In the case where one deletes an already-non-existing variable, or sets a variable to the value it already has, there is no point in writing the environment back, thus reducing wear on the underlying storage device.
Signed-off-by: Rasmus Villemoes rasmus.villemoes@prevas.dk --- tools/env/fw_env.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/tools/env/fw_env.c b/tools/env/fw_env.c index a5d75958e1..87aaa15198 100644 --- a/tools/env/fw_env.c +++ b/tools/env/fw_env.c @@ -110,6 +110,7 @@ struct environment { unsigned char *flags; char *data; enum flag_scheme flag_scheme; + int dirty; };
static struct environment environment = { @@ -508,6 +509,9 @@ int fw_env_flush(struct env_opts *opts) if (!opts) opts = &default_opts;
+ if (!environment.dirty) + return 0; + /* * Update CRC */ @@ -553,7 +557,8 @@ int fw_env_write(char *name, char *value)
deleting = (oldval && !(value && strlen(value))); creating = (!oldval && (value && strlen(value))); - overwriting = (oldval && (value && strlen(value))); + overwriting = (oldval && (value && strlen(value) && + strcmp(oldval, value)));
/* check for permission */ if (deleting) { @@ -593,6 +598,7 @@ int fw_env_write(char *name, char *value) /* Nothing to do */ return 0;
+ environment.dirty = 1; if (deleting || overwriting) { if (*++nxt == '\0') { *env = '\0'; @@ -1441,6 +1447,7 @@ int fw_env_open(struct env_opts *opts) "Warning: Bad CRC, using default environment\n"); memcpy(environment.data, default_environment, sizeof(default_environment)); + environment.dirty = 1; } } else { flag0 = *environment.flags; @@ -1503,6 +1510,7 @@ int fw_env_open(struct env_opts *opts) "Warning: Bad CRC, using default environment\n"); memcpy(environment.data, default_environment, sizeof(default_environment)); + environment.dirty = 1; dev_current = 0; } else { switch (environment.flag_scheme) {