[PATCH v2 11/13] env: Make return value of env_get_f() behave like sprintf() on success

Marek Behún
2021-10-13T15:48:26Z

From: Marek Behún <marek.behun@nic.cz>

Currently the env_get_f() function's return value behaves weirdly: it
returns the number of bytes written into `buf`, but whether this is
excluding the terminating NULL-byte or including it depends on whether
there was enough space in `buf`.

Change the function to always return the actual length of the value of
the environment variable (excluding the terminating NULL-byte) on
success. This makes it behave like sprintf().

All users of this function in U-Boot are compatible with this change.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
---
cmd/nvedit.c | 8 +++++---
include/env.h | 6 ++----
2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/cmd/nvedit.c b/cmd/nvedit.c
index 08288fad10..8989c85d20 100644
--- a/cmd/nvedit.c
+++ b/cmd/nvedit.c
@@ -736,7 +736,7 @@ int env_get_f(const char *name, char *buf, unsigned len)

for (p = env; *p != '\0'; p = end + 1) {
const char *value;
- int n;
+ int n, res;

for (end = p; *end != '\0'; ++end)
if (end - env >= CONFIG_ENV_SIZE)
@@ -746,11 +746,13 @@ int env_get_f(const char *name, char *buf, unsigned len)
if (value == NULL)
continue;

+ res = end - value;
+
/* found; copy out */
for (n = 0; n < len; ++n, ++buf) {
*buf = *value++;
if (*buf == '\0')
- return n;
+ return res;
}

if (n)
@@ -759,7 +761,7 @@ int env_get_f(const char *name, char *buf, unsigned len)
printf("env_buf [%u bytes] too small for value of \"%s\"\n",
len, name);

- return n;
+ return res;
}

return -1;
diff --git a/include/env.h b/include/env.h
index 220ab979d9..ee5e30d036 100644
--- a/include/env.h
+++ b/include/env.h
@@ -120,10 +120,8 @@ char *from_env(const char *envvar);
* support reading the value (slowly) and some will not.
*
* @varname: Variable to look up
- * @return number of bytes written into @buf, excluding the terminating
- * NULL-byte if there was enough space in @buf, and including the
- * terminating NULL-byte if there wasn't enough space, or -1 if the
- * variable is not found
+ * @return actual length of the variable value excluding the terminating
+ * NULL-byte, or -1 if the variable is not found
*/
int env_get_f(const char *name, char *buf, unsigned int len);

--
2.32.0