Introduce a macro for appending formatted text to the output buffer.
Eliminate the local variables 'shift' and 'freechar'. Move the
code for freeing a temporary buffer to the end of the function.
Handle snprintf() conversion errors. This patch avoids that gcc 7
reports the following warning:
dmparser.c:137:20: warning: '__builtin_snprintf' output truncated before the
last format character [-Wformat-truncation=]
snprintf(p, 1, "\n");
^
Signed-off-by: Bart Van Assche <[email protected]>
---
libmultipath/dmparser.c | 67 +++++++++++++++++++++++--------------------------
1 file changed, 31 insertions(+), 36 deletions(-)
diff --git a/libmultipath/dmparser.c b/libmultipath/dmparser.c
index 469e60d2..ba09dc72 100644
--- a/libmultipath/dmparser.c
+++ b/libmultipath/dmparser.c
@@ -45,6 +45,22 @@ merge_words (char ** dst, char * word, int space)
return 0;
}
+#define APPEND(p, end, args...)
\
+({ \
+ int ret; \
+ \
+ ret = snprintf(p, end - p, ##args); \
+ if (ret < 0) { \
+ condlog(0, "%s: conversion error", mp->alias); \
+ goto err; \
+ } \
+ p += ret; \
+ if (p >= end) { \
+ condlog(0, "%s: params too small", mp->alias); \
+ goto err; \
+ } \
+})
+
/*
* Transforms the path group vector into a proper device map string
*/
@@ -52,10 +68,10 @@ int
assemble_map (struct multipath * mp, char * params, int len)
{
int i, j;
- int shift, freechar;
int minio;
int nr_priority_groups, initial_pg_nr;
char * p, * f;
+ const char *const end = params + len;
char no_path_retry[] = "queue_if_no_path";
char retain_hwhandler[] = "retain_attached_hw_handler";
struct pathgroup * pgp;
@@ -63,7 +79,6 @@ assemble_map (struct multipath * mp, char * params, int len)
minio = mp->minio;
p = params;
- freechar = len;
nr_priority_groups = VECTOR_SIZE(mp->pg);
initial_pg_nr = (nr_priority_groups ? mp->bestpg : 0);
@@ -86,29 +101,13 @@ assemble_map (struct multipath * mp, char * params, int
len)
if (mp->retain_hwhandler == RETAIN_HWHANDLER_ON)
add_feature(&f, retain_hwhandler);
- shift = snprintf(p, freechar, "%s %s %i %i",
- f, mp->hwhandler,
- nr_priority_groups, initial_pg_nr);
-
- FREE(f);
-
- if (shift >= freechar) {
- condlog(0, "%s: params too small", mp->alias);
- return 1;
- }
- p += shift;
- freechar -= shift;
+ APPEND(p, end, "%s %s %i %i", f, mp->hwhandler, nr_priority_groups,
+ initial_pg_nr);
vector_foreach_slot (mp->pg, pgp, i) {
pgp = VECTOR_SLOT(mp->pg, i);
- shift = snprintf(p, freechar, " %s %i 1", mp->selector,
- VECTOR_SIZE(pgp->paths));
- if (shift >= freechar) {
- condlog(0, "%s: params too small", mp->alias);
- return 1;
- }
- p += shift;
- freechar -= shift;
+ APPEND(p, end, " %s %i 1", mp->selector,
+ VECTOR_SIZE(pgp->paths));
vector_foreach_slot (pgp->paths, pp, j) {
int tmp_minio = minio;
@@ -118,28 +117,24 @@ assemble_map (struct multipath * mp, char * params, int
len)
tmp_minio = minio * pp->priority;
if (!strlen(pp->dev_t) ) {
condlog(0, "dev_t not set for '%s'", pp->dev);
- return 1;
+ goto err;
}
- shift = snprintf(p, freechar, " %s %d",
- pp->dev_t, tmp_minio);
- if (shift >= freechar) {
- condlog(0, "%s: params too small", mp->alias);
- return 1;
- }
- p += shift;
- freechar -= shift;
+ APPEND(p, end, " %s %d", pp->dev_t, tmp_minio);
}
}
- if (freechar < 1) {
- condlog(0, "%s: params too small", mp->alias);
- return 1;
- }
- snprintf(p, 1, "\n");
+ APPEND(p, end, "\n");
+ FREE(f);
condlog(3, "%s: assembled map [%s]", mp->alias, params);
return 0;
+
+err:
+ FREE(f);
+ return 1;
}
+#undef APPEND
+
int disassemble_map(vector pathvec, char *params, struct multipath *mpp,
int is_daemon)
{
--
2.12.2
--
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