Quote from https://patchwork.ozlabs.org/patch/1104244/#2210814:
----------8<-----------
strncmp() is chosen for the sake of paranoid/defensive programming.
Indeed, strncmp() is not really needed when comparing a variable
with a string literal. We expect strcmp() to behave safely even if the
string variable is not NUL-terminated.
In the same scenario, Linux v5.2-rc7 uses both strcmp() and strncmp(),
but the frequency of strcmp() is higher:
$ git --version
git version 2.22.0
$ (Linux 5.2-rc7) git grep -En 'strncmp\([^"]*"[[:alnum:]]+"' | wc -l
1066
$ (Linux 5.2-rc7) git grep -En 'strcmp\([^"]*"[[:alnum:]]+"' | wc -l
1968
A quick "strcmp vs strncmp" object size test shows that strcmp()
generates smaller memory footprint (gcc-8, x86_64):
$ (U-Boot) size cmd/bcb-strncmp.o cmd/bcb-strcmp.o
text data bss dec hex filename
3373 400 2048 5821 16bd cmd/bcb-strncmp.o
3314 400 2048 5762 1682 cmd/bcb-strcmp.o
So, overall, I agree to use strcmp() whenever variables are compared
with string literals.
----------8<-----------
Fixes: db7b7a05b267 ("cmd: Add 'bcb' command to read/modify/write BCB fields")
Reported-by: Simon Glass <s...@chromium.org>
Signed-off-by: Eugeniu Rosca <ero...@de.adit-jv.com>
---
v2:
- Fixed accidental rename of field/size variables in bcb_field_get()
v1:
- https://patchwork.ozlabs.org/patch/1131306/
---
cmd/bcb.c | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)
diff --git a/cmd/bcb.c b/cmd/bcb.c
index 3b1c7434e287..fa9fdeeb0dfc 100644
--- a/cmd/bcb.c
+++ b/cmd/bcb.c
@@ -24,17 +24,17 @@ static struct bootloader_message bcb = { { 0 } };
static int bcb_cmd_get(char *cmd)
{
- if (!strncmp(cmd, "load", sizeof("load")))
+ if (!strcmp(cmd, "load"))
return BCB_CMD_LOAD;
- if (!strncmp(cmd, "set", sizeof("set")))
+ if (!strcmp(cmd, "set"))
return BCB_CMD_FIELD_SET;
- if (!strncmp(cmd, "clear", sizeof("clear")))
+ if (!strcmp(cmd, "clear"))
return BCB_CMD_FIELD_CLEAR;
- if (!strncmp(cmd, "test", sizeof("test")))
+ if (!strcmp(cmd, "test"))
return BCB_CMD_FIELD_TEST;
- if (!strncmp(cmd, "store", sizeof("store")))
+ if (!strcmp(cmd, "store"))
return BCB_CMD_STORE;
- if (!strncmp(cmd, "dump", sizeof("dump")))
+ if (!strcmp(cmd, "dump"))
return BCB_CMD_FIELD_DUMP;
else
return -1;
@@ -85,19 +85,19 @@ err:
static int bcb_field_get(char *name, char **field, int *size)
{
- if (!strncmp(name, "command", sizeof("command"))) {
+ if (!strcmp(name, "command")) {
*field = bcb.command;
*size = sizeof(bcb.command);
- } else if (!strncmp(name, "status", sizeof("status"))) {
+ } else if (!strcmp(name, "status")) {
*field = bcb.status;
*size = sizeof(bcb.status);
- } else if (!strncmp(name, "recovery", sizeof("recovery"))) {
+ } else if (!strcmp(name, "recovery")) {
*field = bcb.recovery;
*size = sizeof(bcb.recovery);
- } else if (!strncmp(name, "stage", sizeof("stage"))) {
+ } else if (!strcmp(name, "stage")) {
*field = bcb.stage;
*size = sizeof(bcb.stage);
- } else if (!strncmp(name, "reserved", sizeof("reserved"))) {
+ } else if (!strcmp(name, "reserved")) {
*field = bcb.reserved;
*size = sizeof(bcb.reserved);
} else {
--
2.22.0
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