Merge remote-tracking branch 'origin/master' into fix/htscore-745

The path the guard admits (HTS_URLMAXSIZE) plus ".txt" is longer than macOS
accepts, so fopen() failed there. The case could not tell a fixed build from an
unfixed one anyway; what is left covers the guard and the rename on both entry
points.

Signed-off-by: Xavier Roche <roche@httrack.com>
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Signed-off-by: Xavier Roche <roche@httrack.com>

src/htscore.c

@@ -2693,7 +2693,11 @@ HTSEXT_API int structcheck(const char *path) {
       if (!S_ISDIR(st.st_mode)) {
 #if HTS_REMOVE_ANNOYING_INDEX
         if (S_ISREG(st.st_mode)) {      /* Regular file in place ; move it and create directory */
-          sprintf(tmpbuf, "%s.txt", file);
+          /* bounded here, not by the path-length guard far above */
+          if (!sprintfbuff(tmpbuf, "%s.txt", file)) {
+            errno = ENAMETOOLONG;
+            return -1;
+          }
           if (rename(file, tmpbuf) != 0) {      /* Can't rename regular file */
             return -1;
           }
@@ -2801,7 +2805,11 @@ HTSEXT_API int structcheck_utf8(const char *path) {
       if (!S_ISDIR(st.st_mode)) {
 #if HTS_REMOVE_ANNOYING_INDEX
         if (S_ISREG(st.st_mode)) {      /* Regular file in place ; move it and create directory */
-          sprintf(tmpbuf, "%s.txt", file);
+          /* bounded here, not by the path-length guard far above */
+          if (!sprintfbuff(tmpbuf, "%s.txt", file)) {
+            errno = ENAMETOOLONG;
+            return -1;
+          }
           if (RENAME(file, tmpbuf) != 0) {      /* Can't rename regular file */
             return -1;
           }

src/htsselftest.c

@@ -3262,6 +3262,81 @@ static int st_topindex(httrackp *opt, int argc, char **argv) {
   return 0;
 }
 
+/* Build a path of exactly len chars under base; returns that length. */
+static size_t st_structcheck_longpath(char *dst, size_t dstsize,
+                                      const char *base, size_t len) {
+  size_t n = strlen(base);
+
+  assertf(len < dstsize && n + 2 <= len);
+  memmove(dst, base, n);
+  while (n < len) {
+    size_t seg = len - n - 1;
+
+    if (seg > 200) /* stay under the usual 255-byte component limit */
+      seg = len - n == 202 ? 199 : 200; /* never leave a bare separator */
+    dst[n++] = '/';
+    memset(dst + n, 'x', seg);
+    n += seg;
+  }
+  dst[n] = '\0';
+  return n;
+}
+
+/* The path guard, and the <name>.txt rename structcheck() performs when a
+   regular file sits where a directory has to go (#745). */
+static int st_structcheck(httrackp *opt, int argc, char **argv) {
+  char BIGSTK path[HTS_URLMAXSIZE * 2];
+  char BIGSTK target[HTS_URLMAXSIZE * 2];
+  FILE *fp;
+
+  (void) opt;
+  if (argc < 1) {
+    fprintf(stderr, "usage: -#test=structcheck <writable directory>\n");
+    return 1;
+  }
+
+  /* over the guard: refused before a single directory is created */
+  st_structcheck_longpath(path, sizeof(path), argv[0], HTS_URLMAXSIZE + 1);
+  errno = 0;
+  assertf(structcheck(path) == -1);
+  assertf(errno == EINVAL);
+  errno = 0;
+  assertf(structcheck_utf8(path) == -1);
+  assertf(errno == EINVAL);
+  {
+    char *const sep = strchr(path + strlen(argv[0]) + 1, '/');
+
+    assertf(sep != NULL);
+    sep[1] = '\0'; /* the outermost component it would have created */
+    assertf(!dir_exists(path));
+  }
+
+  /* a regular file where a directory belongs is renamed to <name>.txt */
+  snprintf(path, sizeof(path), "%s/sc", argv[0]);
+  fp = fopen(path, "wb");
+  assertf(fp != NULL);
+  fclose(fp);
+  snprintf(path, sizeof(path), "%s/sc/sub/", argv[0]);
+  assertf(structcheck(path) == 0);
+  assertf(dir_exists(path));
+  snprintf(target, sizeof(target), "%s/sc.txt", argv[0]);
+  assertf(fexist(target));
+
+  /* the utf-8 entry point carries the same rename */
+  snprintf(path, sizeof(path), "%s/u8", argv[0]);
+  fp = FOPEN(path, "wb");
+  assertf(fp != NULL);
+  fclose(fp);
+  snprintf(path, sizeof(path), "%s/u8/sub/", argv[0]);
+  assertf(structcheck_utf8(path) == 0);
+  assertf(dir_exists(path));
+  snprintf(target, sizeof(target), "%s/u8.txt", argv[0]);
+  assertf(fexist_utf8(target));
+
+  printf("structcheck self-test OK\n");
+  return 0;
+}
+
 /* Each inplace_escape_*() must equal escape_*() on a copy. */
 static int st_inplace_escape(httrackp *opt, int argc, char **argv) {
   /* >255 bytes forces the helper's malloct path, not the stack buffer */
@@ -6421,6 +6496,9 @@ static const struct selftest_entry {
     {"useragent", "", "default User-Agent self-test", st_useragent},
     {"makeindex", "[dir]", "hts_finish_makeindex footer/refresh self-test",
      st_makeindex},
+    {"structcheck", "<dir>",
+     "structcheck path guard and the <name>.txt rename it performs",
+     st_structcheck},
     {"topindex", "[dir]",
      "hts_buildtopindex charset handling of a non-ASCII project dir",
      st_topindex},

tests/01_engine-structcheck.test

@@ -0,0 +1,12 @@
+#!/bin/bash
+#
+# structcheck(): the path-length guard, and the <name>.txt rename that once
+# built its target with an unbounded sprintf (#745).
+
+set -euo pipefail
+
+dir=$(mktemp -d)
+trap 'rm -rf "$dir"' EXIT
+
+httrack -O /dev/null -#test=structcheck "$dir" |
+    grep -q "structcheck self-test OK"

tests/Makefile.am

@@ -81,6 +81,7 @@ TESTS = \
 	01_engine-status.test \
 	01_engine-stripquery.test \
 	01_engine-strsafe.test \
+	01_engine-structcheck.test \
 	01_engine-syscharset.test \
 	01_engine-threadwait.test \
 	01_engine-topindex.test \