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treewide: Comply with CERT C rule ERR33-C for snprintf()

Browse source 
clang-tidy, starting from LLVM version 16, up to at least LLVM version
19, now checks that we detect and handle errors for snprintf() as
requested by CERT C rule ERR33-C. These warnings were logged with LLVM
version 19.1.2 (at least Debian and Fedora match):

/home/sbrivio/passt/arch.c:43:3: error: the value returned by this function should not be disregarded; neglecting it may lead to errors [cert-err33-c,-warnings-as-errors]
   43 |                 snprintf(new_path, PATH_MAX + sizeof(".avx2"), "%s.avx2", exe);
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/sbrivio/passt/arch.c:43:3: note: cast the expression to void to silence this warning
/home/sbrivio/passt/conf.c:577:4: error: the value returned by this function should not be disregarded; neglecting it may lead to errors [cert-err33-c,-warnings-as-errors]
  577 |                         snprintf(netns, PATH_MAX, "/proc/%ld/ns/net", pidval);
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/sbrivio/passt/conf.c:577:4: note: cast the expression to void to silence this warning
/home/sbrivio/passt/conf.c:579:5: error: the value returned by this function should not be disregarded; neglecting it may lead to errors [cert-err33-c,-warnings-as-errors]
  579 |                                 snprintf(userns, PATH_MAX, "/proc/%ld/ns/user",
      |                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  580 |                                          pidval);
      |                                          ~~~~~~~
/home/sbrivio/passt/conf.c:579:5: note: cast the expression to void to silence this warning
/home/sbrivio/passt/pasta.c:105:2: error: the value returned by this function should not be disregarded; neglecting it may lead to errors [cert-err33-c,-warnings-as-errors]
  105 |         snprintf(ns, PATH_MAX, "/proc/%i/ns/net", pasta_child_pid);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/sbrivio/passt/pasta.c:105:2: note: cast the expression to void to silence this warning
/home/sbrivio/passt/pasta.c:242:2: error: the value returned by this function should not be disregarded; neglecting it may lead to errors [cert-err33-c,-warnings-as-errors]
  242 |         snprintf(uidmap, BUFSIZ, "0 %u 1", uid);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/sbrivio/passt/pasta.c:242:2: note: cast the expression to void to silence this warning
/home/sbrivio/passt/pasta.c:243:2: error: the value returned by this function should not be disregarded; neglecting it may lead to errors [cert-err33-c,-warnings-as-errors]
  243 |         snprintf(gidmap, BUFSIZ, "0 %u 1", gid);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/sbrivio/passt/pasta.c:243:2: note: cast the expression to void to silence this warning
/home/sbrivio/passt/tap.c:1155:4: error: the value returned by this function should not be disregarded; neglecting it may lead to errors [cert-err33-c,-warnings-as-errors]
 1155 |                         snprintf(path, UNIX_PATH_MAX - 1, UNIX_SOCK_PATH, i);
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/sbrivio/passt/tap.c:1155:4: note: cast the expression to void to silence this warning

Don't silence the warnings as they might actually have some merit. Add
an snprintf_check() function, instead, checking that we're not
truncating messages while printing to buffers, and terminate if the
check fails.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Stefano Brivio 2024-10-24 23:25:33 +02:00
parent 988a4d75f8
commit 98efe7c2fd
6 changed files with 57 additions and 10 deletions

2
util.h
View file

@ -11,6 +11,7 @@
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <arpa/inet.h>
@ -200,6 +201,7 @@ int write_file(const char *path, const char *buf);
int write_all_buf(int fd, const void *buf, size_t len);
int write_remainder(int fd, const struct iovec *iov, size_t iovcnt, size_t skip);
void close_open_files(int argc, char **argv);
bool snprintf_check(char *str, size_t size, const char *format, ...);
/**
* af_name() - Return name of an address family