gzread(3) doesn't always set errno, so use gzerror(3)

Compression errors from libz don't set errno.

OK mlarkin@

diff --git a/usr.sbin/vmd/loadfile_elf.c b/usr.sbin/vmd/loadfile_elf.c
index 8a18cb3..7088792 100644 (file)
--- a/usr.sbin/vmd/loadfile_elf.c
+++ b/usr.sbin/vmd/loadfile_elf.c
@@ -1,5 +1,5 @@
 /* $NetBSD: loadfile.c,v 1.10 2000/12/03 02:53:04 tsutsui Exp $ */
-/* $OpenBSD: loadfile_elf.c,v 1.38 2021/04/05 18:09:48 dv Exp $ */
+/* $OpenBSD: loadfile_elf.c,v 1.39 2021/05/04 10:48:51 dv Exp $ */
 
 /*-
  * Copyright (c) 1997 The NetBSD Foundation, Inc.
@@ -482,6 +482,8 @@ push_stack(uint32_t bootargsz, uint32_t end)
 size_t
 mread(gzFile fp, paddr_t addr, size_t sz)
 {
+       const char *errstr = NULL;
+       int errnum = 0;
        size_t ct;
        size_t i, rd, osz;
        char buf[PAGE_SIZE];
@@ -501,7 +503,11 @@ mread(gzFile fp, paddr_t addr, size_t sz)
                        ct = sz;
 
                if ((size_t)gzread(fp, buf, ct) != ct) {
-                       log_warn("%s: error %d in mread", __progname, errno);
+                       errstr = gzerror(fp, &errnum);
+                       if (errnum == Z_ERRNO)
+                               errnum = errno;
+                       log_warnx("%s: error %d in mread, %s", __progname,
+                           errnum, errstr);
                        return (0);
                }
                rd += ct;
@@ -525,7 +531,11 @@ mread(gzFile fp, paddr_t addr, size_t sz)
                        ct = PAGE_SIZE;
 
                if ((size_t)gzread(fp, buf, ct) != ct) {
-                       log_warn("%s: error %d in mread", __progname, errno);
+                       errstr = gzerror(fp, &errnum);
+                       if (errnum == Z_ERRNO)
+                               errnum = errno;
+                       log_warnx("%s: error %d in mread, %s", __progname,
+                           errnum, errstr);
                        return (0);
                }
                rd += ct;