gcc8 complains with:
lsmmc.c: In function 'read_file':
lsmmc.c:356:3: error: 'strncpy' accessing 4096 bytes at \
offsets 0 and 1 overlaps 4095 bytes at offset 1 [-Werror=restrict]
strncpy(&line[0], &line[1], sizeof(line));
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The man page for strncpy() does not clearly state whether it's safe to
use overlapping memory regions while copying; for the similar strcpy()
this is prohibited, so I would also assume this for strncpy().
So let's refactor this part.
Reported-by: Simon Tretter
Signed-off-by: Michael Heimpold <mhei@xxxxxxxxxxx>
---
lsmmc.c | 25 +++++++++++++++----------
1 file changed, 15 insertions(+), 10 deletions(-)
diff --git a/lsmmc.c b/lsmmc.c
index c4faa00..d352e74 100644
--- a/lsmmc.c
+++ b/lsmmc.c
@@ -316,8 +316,9 @@ int parse_ids(struct config *config)
/* MMC/SD file parsing functions */
char *read_file(char *name)
{
- char *preparsed;
+ char *start, *end;
char line[4096];
+ int len;
FILE *f;
f = fopen(name, "r");
@@ -326,8 +327,8 @@ char *read_file(char *name)
return NULL;
}
- preparsed = fgets(line, sizeof(line), f);
- if (!preparsed) {
+ start = fgets(line, sizeof(line), f);
+ if (!start) {
if (ferror(f))
fprintf(stderr, "Could not read MMC/SD file '%s'.\n",
name);
@@ -347,15 +348,19 @@ char *read_file(char *name)
return NULL;
}
- line[sizeof(line) - 1] = '\0';
+ /* skip leading white-space */
+ while (isspace(*start))
+ start++;
- while (isspace(line[strlen(line) - 1]))
- line[strlen(line) - 1] = '\0';
-
- while (isspace(line[0]))
- strncpy(&line[0], &line[1], sizeof(line));
+ /* trim trailing white-space */
+ len = strlen(start);
+ if (len) {
+ end = &start[len - 1];
+ while (isspace(*end))
+ *end-- = '\0';
+ }
- return strdup(line);
+ return strdup(start);
}
/* Hexadecimal string parsing functions */
--
2.17.1
