(Note that despite the Debian description, it really seems largely about
warning fixes instead with one zlib modernisation fix as well.)

https://sources.debian.org/data/main/z/zsync/0.6.2-7/debian/patches/update-zlib-functions.patch

Description: Update functions for zlib de-vendoring
Author: Simon Quigley <tsimonq2@debian.org>
Origin: vendor
Forwarded: not-needed
Last-Update: 2025-02-26
--- a/libzsync/zsync.c
+++ b/libzsync/zsync.c
@@ -151,7 +151,7 @@ struct zsync_state *zsync_begin(FILE * f
     char *safelines = NULL;
 
     /* Allocate memory for the object */
-    struct zsync_state *zs = calloc(sizeof *zs, 1);
+    struct zsync_state *zs = calloc(1, sizeof *zs);
 
     if (!zs)
         return NULL;
@@ -210,7 +210,7 @@ struct zsync_state *zsync_begin(FILE * f
             }
             else if (!strcmp(buf, "Blocksize")) {
                 zs->blocksize = atol(p);
-                if (zs->blocksize < 0 || (zs->blocksize & (zs->blocksize - 1))) {
+                if (zs->blocksize & (zs->blocksize - 1)) {
                     fprintf(stderr, "nonsensical blocksize %ld\n", zs->blocksize);
                     free(zs);
                     return NULL;
@@ -240,7 +240,8 @@ struct zsync_state *zsync_begin(FILE * f
 
                 zblock = malloc(nzblocks * sizeof *zblock);
                 if (zblock) {
-                    if (fread(zblock, sizeof *zblock, nzblocks, f) < nzblocks) {
+                    size_t nread = fread(zblock, sizeof *zblock, nzblocks, f);
+                    if (nread < (size_t)nzblocks) {
                         fprintf(stderr, "premature EOF after Z-Map\n");
                         free(zs);
                         return NULL;
@@ -701,7 +702,8 @@ static int zsync_recompress(struct zsync
                     p = skip_zhead(buf);
                     skip = 0;
                 }
-                if (fwrite(p, 1, r - (p - buf), zout) != r - (p - buf)) {
+                size_t out_len = r - (p - buf);
+                if (fwrite(p, 1, out_len, zout) != out_len) {
                     perror("fwrite");
                     rc = -1;
                     goto leave_it;
@@ -714,8 +716,8 @@ static int zsync_recompress(struct zsync
                 rc = -1;
             }
         }
-        if (fclose(g) != 0) {
-            perror("close");
+        if (pclose(g) == -1) {
+            perror("pclose failed");
             rc = -1;
         }
 
@@ -782,7 +784,7 @@ void zsync_configure_zstream_for_zdata(c
         /* Fake an output buffer of 32k filled with data to zlib */
         zstrm->next_out = wbuf + lookback;
         zstrm->avail_out = 0;
-        updatewindow(zstrm, lookback);
+        inflateSetDictionary(zstrm, wbuf, lookback);
     }
 }
 
@@ -922,10 +924,10 @@ static int zsync_receive_data_compressed
         return 0;
 
     /* Now set up for the downloaded block */
-    zr->strm.next_in = buf;
+    zr->strm.next_in = (Bytef *)buf;
     zr->strm.avail_in = len;
 
-    if (zr->strm.total_in == 0 || offset != zr->strm.total_in) {
+    if (zr->strm.total_in == 0 || (uLong)offset != zr->strm.total_in) {
         zsync_configure_zstream_for_zdata(zr->zs, &(zr->strm), offset,
                                           &(zr->outoffset));
 
@@ -939,7 +941,7 @@ static int zsync_receive_data_compressed
                     "data didn't align with block boundary in compressed stream\n");
             return 1;
         }
-        zr->strm.next_in = buf;
+        zr->strm.next_in = (Bytef *)buf;
         zr->strm.avail_in = len;
     }
 
@@ -952,6 +954,7 @@ static int zsync_receive_data_compressed
         switch (rc) {
         case Z_STREAM_END:
             eoz = 1;
+            [[fallthrough]];
         case Z_BUF_ERROR:
         case Z_OK:
             if (zr->strm.avail_out == 0 || eoz) {
--- a/libzsync/zmap.c
+++ b/libzsync/zmap.c
@@ -359,5 +359,8 @@ void configure_zstream_for_zdata(const s
     *poutoffset = zm->e[i].outbytes;
 
     /* Align with the bitstream */
-    inflate_advance(zs, zoffset, zm->e[i].inbits % 8, !zm->e[i].blockcount);
+    int ret;
+    do {
+        ret = inflate(zs, Z_SYNC_FLUSH);
+    } while (ret == Z_OK);
 }
--- a/make.c
+++ b/make.c
@@ -316,7 +316,7 @@ void do_zstream(FILE * fin, FILE * fout,
             /* If we passed a block boundary in the uncompressed data, record the
              * next available point at which we could stop or start decompression.
              * Write a zmap delta with the 1st when we see the 2nd, etc */
-            if (want_zdelta && inflateSafePoint(&zs)) {
+            if (want_zdelta && inflateSyncPoint(&zs)) {
                 long long cur_in = header_bits + in_position(&zs);
                 if (midblock_in) {
                     write_zmap_delta(&prev_in, &prev_out, midblock_in,
@@ -718,7 +718,7 @@ int main(int argc, char **argv) {
     read_stream_write_blocksums(instream, tf);
 
     {   /* Decide how long a rsum hash and checksum hash per block we need for this file */
-        seq_matches = len > blocksize ? 2 : 1;
+        seq_matches = ((off_t)len > (off_t)blocksize) ? 2 : 1;
         rsum_len = ceil(((log(len) + log(blocksize)) / log(2) - 8.6) / seq_matches / 8);
 
         /* min and max lengths of rsums to store */
@@ -836,7 +836,7 @@ int main(int argc, char **argv) {
                     fprintf(fout, "MTime: %s\n", buf);
             }
             else {
-                fprintf(stderr, "error converting %d to struct tm\n", mtime);
+                fprintf(stderr, "error converting %ld to struct tm\n", (long)mtime);
             }
         }
     }
--- a/http.c
+++ b/http.c
@@ -554,9 +554,10 @@ static int range_fetch_set_url(struct ra
     if (rf->authh) free(rf->authh);
 
     /* Get host:port for Host: header */
-    if (strcmp(cport, "http") != 0)
-        snprintf(rf->hosth, sizeof(rf->hosth), "%s:%s", hostn, cport);
-    else
+    if (strcmp(cport, "http") != 0) {
+        strncpy(rf->hosth, hostn, sizeof(rf->hosth) - 1);
+        rf->hosth[sizeof(rf->hosth) - 1] = '\0';
+    } else
         snprintf(rf->hosth, sizeof(rf->hosth), "%s", hostn);
 
     if (proxy) {