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tools: mkcapsule builds warning-free -- the truncations impossible or handled (#143)

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The kernel build's only warnings were five -Wformat-truncation in mkcapsule's
--resolve: two snprintf copies of a capsule name into the claim registry, and
the capsule's path built from base_dir and its name.

- The names: both are char[CAPSULE_NAME_MAX], and names are checked to fit when
  read (line 335) -- copied whole with memcpy, nothing to truncate.
- The path: base_dir may be up to 4095 bytes, so it can be cut, and a cut path
  names another file -- now refused, the capsule left unchanged and counted
  rejected, with the reason.

Seen to fail first: built with -Werror=format-truncation, 5 errors. After: 0,
and 0 warnings with the kernel's flags; the manifest it writes is
byte-identical, --lint passes. The too-long-path refusal is on --resolve's
interactive conflict path and was not driven by a test. CLAUDE.md's count of
open warnings corrected.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017RzZgrf7V7Zk2iczBXDRbm
This commit is contained in:
Claude
2026-11-12 15:29:13 +00:00
parent c0b714645f
commit 216947a4d4
2 changed files with 12 additions and 5 deletions
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tools/mkcapsule.c
+9 -3
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@@ -1272,7 +1272,7 @@ static int cmd_resolve(const char *dir) {
if (!collides) {
ClaimEntry *dest = prior ? prior : &claim_registry[claim_count++];
snprintf(dest->name, CAPSULE_NAME_MAX, "%s", m->name);
memcpy(dest->name, m->name, CAPSULE_NAME_MAX); /* same-sized arrays: a whole copy, no truncation (#143) */
dest->hash = m->hash;
dest->block_count = m->block_count;
memcpy(dest->blocks, m->blocks, (size_t)m->block_count * sizeof(int));
@@ -1308,7 +1308,13 @@ static int cmd_resolve(const char *dir) {
fprintf(stderr, " %d -> %d\n", m->blocks[j], m->blocks[j] + delta);
}
char fpath[MAX_PATH_LEN];
snprintf(fpath, sizeof(fpath), "%s/%s", base_dir, m->name);
int flen = snprintf(fpath, sizeof(fpath), "%s/%s", base_dir, m->name);
if (flen < 0 || (size_t)flen >= sizeof(fpath)) { /* a cut path names another file (#143) */
fprintf(stderr, " ERROR: the path of %s is longer than %d bytes -- left unchanged\n",
m->name, MAX_PATH_LEN - 1);
rejected++;
continue;
}
/* capsule name uses ':' for subdirectories; the real path uses '/' */
for (char *p = fpath; *p; p++) if (*p == ':') *p = '/';
@@ -1321,7 +1327,7 @@ static int cmd_resolve(const char *dir) {
delta, reason);
for (int j = 0; j < m->block_count; j++) m->blocks[j] += delta;
ClaimEntry *dest = prior ? prior : &claim_registry[claim_count++];
snprintf(dest->name, CAPSULE_NAME_MAX, "%s", m->name);
memcpy(dest->name, m->name, CAPSULE_NAME_MAX); /* as below: same-sized arrays (#143) */
dest->hash = m->hash;
dest->block_count = m->block_count;
memcpy(dest->blocks, m->blocks, (size_t)m->block_count * sizeof(int));