Rename/move xmemcmp() (which doesn't exit) to smemcmp(), and add x prefix

to notstdio() while there.

15 files changed, 66 insertions, 67 deletions

diff --git a/lib/env.c b/lib/env.c
index 7bcf5103..d47e8d23 100644
--- a/lib/env.c
+++ b/lib/env.c
@@ -61,7 +61,7 @@ char *xsetenv(char *name, char *val)
 
   for (i = 0; environ[i]; i++) {
     // Drop old entry, freeing as appropriate. Assumes no duplicates.
-    if (!xmemcmp(name, environ[i], len) && environ[i][len]=='=') {
+    if (!smemcmp(name, environ[i], len) && environ[i][len]=='=') {
       if (i<toys.envc-1) toys.envc--;
       else free(environ[i]);
       j++;
diff --git a/lib/lib.c b/lib/lib.c
index 8d997da7..1d620b38 100644
--- a/lib/lib.c
+++ b/lib/lib.c
@@ -738,7 +738,7 @@ void loopfiles_rw(char **argv, int flags, int permissions,
     // Inability to open a file prints a warning, but doesn't exit.
 
     if (!strcmp(*argv, "-")) fd = 0;
-    else if (0>(fd = notstdio(open(*argv, flags, permissions))) && !failok) {
+    else if (0>(fd = xnotstdio(open(*argv, flags, permissions))) && !failok) {
       perror_msg_raw(*argv);
       if (!anyway) continue;
     }
@@ -1492,7 +1492,7 @@ int is_tar_header(void *pkt)
   char *p = pkt;
   int i = 0;
 
-  if (p[257] && xmemcmp("ustar", p+257, 5)) return 0;
+  if (p[257] && smemcmp("ustar", p+257, 5)) return 0;
   if (p[148] != '0' && p[148] != ' ') return 0;
   sscanf(p+148, "%8o", &i);
 
@@ -1550,3 +1550,15 @@ void octal_deslash(char *s)
 
   *o = 0;
 }
+
+// ASAN flips out about memcmp("a", "abc", 4) but the result is well-defined.
+// This one's guaranteed to stop at len _or_ the first difference.
+int smemcmp(char *one, char *two, unsigned long len)
+{
+  int ii = 0;
+
+  while (len--) if ((ii = *one++ - *two++)) break;
+
+  return ii;
+}
+
diff --git a/lib/lib.h b/lib/lib.h
index 593ac3b2..3127abff 100644
--- a/lib/lib.h
+++ b/lib/lib.h
@@ -103,7 +103,6 @@ struct dirtree *dirtree_read(char *path, int (*callback)(struct dirtree *node));
 #define ABS_LAST 8 // don't resolve symlink in last path component
 
 // xwrap.c
-int xmemcmp(char *one, char *two, unsigned long len);
 void xstrncpy(char *dest, char *src, size_t size);
 void xstrncat(char *dest, char *src, size_t size);
 _Noreturn void _xexit(void);
@@ -146,7 +145,7 @@ int xopenro(char *path);
 void xpipe(int *pp);
 void xclose(int fd);
 int xdup(int fd);
-int notstdio(int fd);
+int xnotstdio(int fd);
 FILE *xfdopen(int fd, char *mode);
 FILE *xfopen(char *path, char *mode);
 size_t xread(int fd, void *buf, size_t len);
@@ -273,6 +272,7 @@ unsigned tar_cksum(void *data);
 int is_tar_header(void *pkt);
 char *elf_arch_name(int type);
 void octal_deslash(char *s);
+int smemcmp(char *one, char *two, unsigned long len);
 
 #define HR_SPACE  1 // Space between number and units
 #define HR_B      2 // Use "B" for single byte units
diff --git a/lib/tty.c b/lib/tty.c
index 1bb10d61..3f26976e 100644
--- a/lib/tty.c
+++ b/lib/tty.c
@@ -22,7 +22,7 @@ int tty_fd(void)
 
   for (i = 0; i<3; i++) if (isatty(j = (i+1)%3)) return j;
 
-  return notstdio(open("/dev/tty", O_RDWR));
+  return xnotstdio(open("/dev/tty", O_RDWR));
 }
 
 // Query size of terminal (without ANSI probe fallback).
diff --git a/lib/xwrap.c b/lib/xwrap.c
index e1d242ff..5ea47d4c 100644
--- a/lib/xwrap.c
+++ b/lib/xwrap.c
@@ -9,17 +9,6 @@
 
 #include "toys.h"
 
-// ASAN flips out about memcmp("a", "abc", 4) but the result is well-defined.
-// This one's guaranteed to stop at len _or_ the first difference.
-int xmemcmp(char *one, char *two, unsigned long len)
-{
-  int ii = 0;
-
-  while (len--) if ((ii = *one++ - *two++)) break;
-
-  return ii;
-}
-
 // strcpy and strncat with size checking. Size is the total space in "dest",
 // including null terminator. Exit if there's not enough space for the string
 // (including space for the null terminator), because silently truncating is
@@ -468,9 +457,7 @@ int xdup(int fd)
   return fd;
 }
 
-// Move file descriptor above stdin/stdout/stderr, using /dev/null to consume
-// old one. (We should never be called with stdin/stdout/stderr closed, but...)
-int notstdio(int fd)
+int xnotstdio(int fd)
 {
   if (fd<0) return fd;
 
@@ -503,13 +490,13 @@ int xtempfile(char *name, char **tempname)
 // Create a file but don't return stdin/stdout/stderr
 int xcreate(char *path, int flags, int mode)
 {
-  return notstdio(xcreate_stdio(path, flags, mode));
+  return xnotstdio(xcreate_stdio(path, flags, mode));
 }
 
 // Open a file descriptor NOT in stdin/stdout/stderr
 int xopen(char *path, int flags)
 {
-  return notstdio(xopen_stdio(path, flags));
+  return xnotstdio(xopen_stdio(path, flags));
 }
 
 // Open read only, treating "-" as a synonym for stdin, defaulting to warn only
diff --git a/toys/other/hexedit.c b/toys/other/hexedit.c
index 2b8f632a..4550dc34 100644
--- a/toys/other/hexedit.c
+++ b/toys/other/hexedit.c
@@ -181,7 +181,7 @@ static void find_prev(int pos)
   size_t len = strlen(TT.search);
 
   for (; pos >= 0; pos--) {
-    if (!xmemcmp(TT.data+pos, TT.search, len)) {
+    if (!smemcmp(TT.data+pos, TT.search, len)) {
       TT.pos = pos;
       return;
     }
diff --git a/toys/other/nbd_client.c b/toys/other/nbd_client.c
index 8a46993e..caa7da61 100644
--- a/toys/other/nbd_client.c
+++ b/toys/other/nbd_client.c
@@ -76,7 +76,7 @@ void nbd_client_main(void)
 
     // Read login data
     xreadall(sock, toybuf, 152);
-    if (xmemcmp(toybuf, "NBDMAGIC\x00\x00\x42\x02\x81\x86\x12\x53", 16))
+    if (smemcmp(toybuf, "NBDMAGIC\x00\x00\x42\x02\x81\x86\x12\x53", 16))
       error_exit("bad login %s:%s", host, port);
     devsize = SWAP_BE64(*(unsigned long long *)(toybuf+16));
     flags = SWAP_BE32(*(int *)(toybuf+24));
diff --git a/toys/other/readelf.c b/toys/other/readelf.c
index 6d01190b..e93e6eb0 100644
--- a/toys/other/readelf.c
+++ b/toys/other/readelf.c
@@ -355,7 +355,7 @@ static void scan_elf()
   char *hdr = TT.elf;
   int type, machine, version, flags, entry, ehsize, phnum, shstrndx, i, j, w;
 
-  if (TT.size < 45 || xmemcmp(hdr, "\177ELF", 4))
+  if (TT.size < 45 || smemcmp(hdr, "\177ELF", 4))
     return error_msg("%s: not ELF", TT.f);
 
   TT.bits = hdr[4] - 1;
diff --git a/toys/other/taskset.c b/toys/other/taskset.c
index 7ca26490..a3d0ffb3 100644
--- a/toys/other/taskset.c
+++ b/toys/other/taskset.c
@@ -127,7 +127,7 @@ void nproc_main(void)
     char *ss;
 
     while ((de = readdir(dd))) {
-      if (xmemcmp(de->d_name, "cpu", 3)) continue;
+      if (smemcmp(de->d_name, "cpu", 3)) continue;
       for (ss = de->d_name+3; isdigit(*ss); ss++);
       if (!*ss) nproc++;
     }
diff --git a/toys/pending/sh.c b/toys/pending/sh.c
index d9abb61a..0f9532e2 100644
--- a/toys/pending/sh.c
+++ b/toys/pending/sh.c
@@ -637,7 +637,7 @@ static int recalculate(long long *dd, char **ss, int lvl)
 
     // Assignment operators: = *= /= %= += -= <<= >>= &= ^= |=
     } else if (lvl<=2 && (*ss)[ii = (-1 != stridx("*/%+-", **ss))
-               +2*!xmemcmp(*ss, "<<", 2)+2*!xmemcmp(*ss, ">>", 2)]=='=')
+               +2*!smemcmp(*ss, "<<", 2)+2*!smemcmp(*ss, ">>", 2)]=='=')
     {
       // TODO: assignments are lower priority BUT must go after variable,
       // come up with precedence checking tests?
@@ -2748,7 +2748,7 @@ static struct sh_process *run_command(void)
 
   // Skip [[ ]] and (( )) contents for now
   if ((s = arg->v[envlen])) {
-    if (!xmemcmp(s, "((", 2)) skiplen = 1;
+    if (!smemcmp(s, "((", 2)) skiplen = 1;
     else if (!strcmp(s, "[[")) while (strcmp(arg->v[envlen+skiplen++], "]]"));
   }
   pp = expand_redir(arg, envlen+skiplen, 0);
@@ -2812,7 +2812,7 @@ static struct sh_process *run_command(void)
 //   Several NOFORK can just NOP in a pipeline? Except ${a?b} still errors
 
   // ((math))
-  else if (!xmemcmp(s = *pp->arg.v, "((", 2)) {
+  else if (!smemcmp(s = *pp->arg.v, "((", 2)) {
     char *ss = s+2;
     long long ll;
 
@@ -3081,7 +3081,7 @@ static int parse_line(char *line, struct sh_pipeline **ppl,
       }
 
       // "for" on its own line is an error.
-      if (arg->c == 1 && ex && !xmemcmp(ex, "do\0A", 4)) {
+      if (arg->c == 1 && ex && !smemcmp(ex, "do\0A", 4)) {
         s = "newline";
         goto flush;
       }
@@ -3175,7 +3175,7 @@ static int parse_line(char *line, struct sh_pipeline **ppl,
         free(s);
         s = 0;
 // TODO can't have ; between "for i" and in or do. (Newline yes, ; no. Why?)
-        if (!arg->c && ex && !xmemcmp(ex, "do\0C", 4)) continue;
+        if (!arg->c && ex && !smemcmp(ex, "do\0C", 4)) continue;
 
       // ;; and friends only allowed in case statements
       } else if (*s == ';') goto flush;
@@ -3187,7 +3187,7 @@ static int parse_line(char *line, struct sh_pipeline **ppl,
       continue;
 
     // a for/select must have at least one additional argument on same line
-    } else if (ex && !xmemcmp(ex, "do\0A", 4)) {
+    } else if (ex && !smemcmp(ex, "do\0A", 4)) {
 
       // Sanity check and break the segment
       if (strncmp(s, "((", 2) && *varend(s)) goto flush;
@@ -3206,7 +3206,7 @@ static int parse_line(char *line, struct sh_pipeline **ppl,
 
     // The "test" part of for/select loops can have (at most) one "in" line,
     // for {((;;))|name [in...]} do
-    if (ex && !xmemcmp(ex, "do\0C", 4)) {
+    if (ex && !smemcmp(ex, "do\0C", 4)) {
       if (strcmp(s, "do")) {
         // can only have one "in" line between for/do, but not with for(())
         if (pl->prev->type == 's') goto flush;
@@ -3238,7 +3238,7 @@ static int parse_line(char *line, struct sh_pipeline **ppl,
 
     // Expecting NULL means any statement (don't care which).
     if (!ex && *expect) {
-      if (pl->prev->type == 'f' && !end && xmemcmp(s, "((", 2)) goto flush;
+      if (pl->prev->type == 'f' && !end && smemcmp(s, "((", 2)) goto flush;
       free(dlist_lpop(expect));
     }
 
diff --git a/toys/posix/cpio.c b/toys/posix/cpio.c
index b5542000..8faf899b 100644
--- a/toys/posix/cpio.c
+++ b/toys/posix/cpio.c
@@ -132,7 +132,7 @@ void cpio_main(void)
       if (empty) error_exit("empty archive");
       else break;
     }
-    if (size != 110 || xmemcmp(toybuf, "070701", 6)) error_exit("bad header");
+    if (size != 110 || smemcmp(toybuf, "070701", 6)) error_exit("bad header");
     tofree = name = strpad(afd, x8u(toybuf+94), 110);
     if (!strcmp("TRAILER!!!", name)) {
       free(tofree);
diff --git a/toys/posix/file.c b/toys/posix/file.c
index acfd28da..e48a5472 100644
--- a/toys/posix/file.c
+++ b/toys/posix/file.c
@@ -177,10 +177,10 @@ static void do_elf_file(int fd)
           goto bad;
         }
 
-        if (n_namesz==4 && !xmemcmp(note+12, "GNU", 4) && n_type==3) {
+        if (n_namesz==4 && !smemcmp(note+12, "GNU", 4) && n_type==3) {
           printf(", BuildID=");
           for (j = 0; j<n_descsz; j++) printf("%02x", note[16+j]);
-        } else if (n_namesz==8 && !xmemcmp(note+12, "Android", 8)) {
+        } else if (n_namesz==8 && !smemcmp(note+12, "Android", 8)) {
           if (n_type==1 /*.android.note.ident*/ && n_descsz >= 4) {
             printf(", for Android %d", (int)elf_int(note+20, 4));
             // NDK r14 and later also include NDK version info. OS binaries
@@ -244,7 +244,7 @@ static void do_regular_file(int fd, char *name)
       s-3, (int)peek_le(s, 2), (int)peek_le(s+2, 2));
 
   // TODO: parsing JPEG for width/height is harder than GIF or PNG.
-  else if (len>32 && !xmemcmp(s, "\xff\xd8", 2)) xputs("JPEG image data");
+  else if (len>32 && !smemcmp(s, "\xff\xd8", 2)) xputs("JPEG image data");
 
   else if (len>8 && strstart(&s, "\xca\xfe\xba\xbe")) {
     unsigned count = peek_be(s, 4), i, arch;
@@ -307,7 +307,7 @@ static void do_regular_file(int fd, char *name)
   else if (len>31 && peek_be(s, 7) == 0xfd377a585a0000UL)
     xputs("xz compressed data");
   else if (len>10 && strstart(&s, "\x1f\x8b")) xputs("gzip compressed data");
-  else if (len>32 && !xmemcmp(s+1, "\xfa\xed\xfe", 3)) {
+  else if (len>32 && !smemcmp(s+1, "\xfa\xed\xfe", 3)) {
     int bit = (*s==0xce) ? 32 : 64;
     char *what = 0;
 
@@ -325,26 +325,26 @@ static void do_regular_file(int fd, char *name)
     else what = NULL;
     if (what) xprintf("%s\n", what);
     else xprintf("(bad type %d)\n", s[9]);
-  } else if (len>36 && !xmemcmp(s, "OggS\x00\x02", 6)) {
+  } else if (len>36 && !smemcmp(s, "OggS\x00\x02", 6)) {
     xprintf("Ogg data");
     // https://wiki.xiph.org/MIMETypesCodecs
-    if (!xmemcmp(s+28, "CELT    ", 8)) xprintf(", celt audio");
-    else if (!xmemcmp(s+28, "CMML    ", 8)) xprintf(", cmml text");
-    else if (!xmemcmp(s+28, "BBCD\0", 5)) xprintf(", dirac video");
-    else if (!xmemcmp(s+28, "\177FLAC", 5)) xprintf(", flac audio");
-    else if (!xmemcmp(s+28, "\x8bJNG\r\n\x1a\n", 8)) xprintf(", jng video");
-    else if (!xmemcmp(s+28, "\x80kate\0\0\0", 8)) xprintf(", kate text");
-    else if (!xmemcmp(s+28, "OggMIDI\0", 8)) xprintf(", midi text");
-    else if (!xmemcmp(s+28, "\x8aMNG\r\n\x1a\n", 8)) xprintf(", mng video");
-    else if (!xmemcmp(s+28, "OpusHead", 8)) xprintf(", opus audio");
-    else if (!xmemcmp(s+28, "PCM     ", 8)) xprintf(", pcm audio");
-    else if (!xmemcmp(s+28, "\x89PNG\r\n\x1a\n", 8)) xprintf(", png video");
-    else if (!xmemcmp(s+28, "Speex   ", 8)) xprintf(", speex audio");
-    else if (!xmemcmp(s+28, "\x80theora", 7)) xprintf(", theora video");
-    else if (!xmemcmp(s+28, "\x01vorbis", 7)) xprintf(", vorbis audio");
-    else if (!xmemcmp(s+28, "YUV4MPEG", 8)) xprintf(", yuv4mpeg video");
+    if (!smemcmp(s+28, "CELT    ", 8)) xprintf(", celt audio");
+    else if (!smemcmp(s+28, "CMML    ", 8)) xprintf(", cmml text");
+    else if (!smemcmp(s+28, "BBCD", 5)) xprintf(", dirac video");
+    else if (!smemcmp(s+28, "\177FLAC", 5)) xprintf(", flac audio");
+    else if (!smemcmp(s+28, "\x8bJNG\r\n\x1a\n", 8)) xprintf(", jng video");
+    else if (!smemcmp(s+28, "\x80kate\0\0", 8)) xprintf(", kate text");
+    else if (!smemcmp(s+28, "OggMIDI", 8)) xprintf(", midi text");
+    else if (!smemcmp(s+28, "\x8aMNG\r\n\x1a\n", 8)) xprintf(", mng video");
+    else if (!smemcmp(s+28, "OpusHead", 8)) xprintf(", opus audio");
+    else if (!smemcmp(s+28, "PCM     ", 8)) xprintf(", pcm audio");
+    else if (!smemcmp(s+28, "\x89PNG\r\n\x1a\n", 8)) xprintf(", png video");
+    else if (!smemcmp(s+28, "Speex   ", 8)) xprintf(", speex audio");
+    else if (!smemcmp(s+28, "\x80theora", 7)) xprintf(", theora video");
+    else if (!smemcmp(s+28, "\x01vorbis", 7)) xprintf(", vorbis audio");
+    else if (!smemcmp(s+28, "YUV4MPEG", 8)) xprintf(", yuv4mpeg video");
     xputc('\n');
-  } else if (len>32 && !xmemcmp(s, "RIF", 3) && !xmemcmp(s+8, "WAVEfmt ", 8)) {
+  } else if (len>32 && !smemcmp(s, "RIF", 3) && !smemcmp(s+8, "WAVEfmt ", 8)) {
     // https://en.wikipedia.org/wiki/WAV
     int le = (s[3] == 'F');
     int format = le ? peek_le(s+20, 2) : peek_be(s+20, 2);
@@ -372,7 +372,7 @@ static void do_regular_file(int fd, char *name)
     else xprintf("unknown format %d", format);
     xputc('\n');
   } else if (len>12 && peek_be(s, 4)==0x10000) xputs("TrueType font");
-  else if (len>12 && !xmemcmp(s, "ttcf\x00", 5)) {
+  else if (len>12 && !smemcmp(s, "ttcf", 5)) {
     xprintf("TrueType font collection, version %d, %d fonts\n",
             (int)peek_be(s+4, 2), (int)peek_be(s+8, 4));
 
@@ -382,14 +382,14 @@ static void do_regular_file(int fd, char *name)
   else if (strstart(&s,"-----BEGIN CERTIFICATE-----")) xputs("PEM certificate");
 
   // https://msdn.microsoft.com/en-us/library/windows/desktop/ms680547(v=vs.85).aspx
-  else if (len>0x70 && !xmemcmp(s, "MZ", 2) &&
-      (magic=peek_le(s+0x3c,4))<len-4 && !xmemcmp(s+magic, "\x50\x45\0", 4)) {
+  else if (len>0x70 && !smemcmp(s, "MZ", 2) &&
+      (magic=peek_le(s+0x3c,4))<len-4 && !smemcmp(s+magic, "\x50\x45\0", 4)) {
 
     // Linux kernel images look like PE files.
     // https://www.kernel.org/doc/Documentation/arm64/booting.txt
     // I've only ever seen LE, 4KiB pages, so ignore flags for now.
-    if (!xmemcmp(s+0x38, "ARMd", 4)) return xputs("Linux arm64 kernel image");
-    else if (!xmemcmp(s+0x202, "HdrS", 4)) {
+    if (!smemcmp(s+0x38, "ARMd", 4)) return xputs("Linux arm64 kernel image");
+    else if (!smemcmp(s+0x202, "HdrS", 4)) {
       // https://www.kernel.org/doc/Documentation/x86/boot.txt
       unsigned ver_off = peek_le(s+0x20e, 2);
 
@@ -418,7 +418,7 @@ static void do_regular_file(int fd, char *name)
     xprintf("x86%s\n", (peek_le(s+magic+4, 2)==0x14c) ? "" : "-64");
 
     // https://en.wikipedia.org/wiki/BMP_file_format
-  } else if (len>0x32 && !xmemcmp(s, "BM", 2) && !peek_be(s+6, 4)) {
+  } else if (len>0x32 && !smemcmp(s, "BM", 2) && !peek_be(s+6, 4)) {
     xprintf("BMP image, %d x %d, %d bpp\n", (int)peek_le(s+18, 4),
             (int)peek_le(s+22,4), (int)peek_le(s+28, 2));
 
@@ -432,7 +432,7 @@ static void do_regular_file(int fd, char *name)
         (int)peek_le(s+12, 4), (int)peek_le(s+20, 4));
 
     // https://android.googlesource.com/platform/system/tools/mkbootimg/+/refs/heads/master/include/bootimg/bootimg.h
-  } else if (len>1632 && !xmemcmp(s, "ANDROID!", 8)) {
+  } else if (len>1632 && !smemcmp(s, "ANDROID!", 8)) {
     xprintf("Android boot image v%d\n", (int)peek_le(s+40, 4));
 
     // https://source.android.com/devices/architecture/dto/partitions
@@ -441,7 +441,7 @@ static void do_regular_file(int fd, char *name)
             (int)peek_be(s+16, 4));
 
     // frameworks/base/core/java/com/android/internal/util/BinaryXmlSerializer.java
-  } else if (len>4 && !xmemcmp(s, "ABX", 3)) {
+  } else if (len>4 && !smemcmp(s, "ABX", 3)) {
     xprintf("Android Binary XML v%d\n", s[3]);
 
     // Text files, including shell scripts.
diff --git a/toys/posix/od.c b/toys/posix/od.c
index a37186cb..c12055e6 100644
--- a/toys/posix/od.c
+++ b/toys/posix/od.c
@@ -133,7 +133,7 @@ static void od_outline(void)
 
   // Handle duplciate lines as *
   if (!FLAG(v) && TT.j != TT.pos && TT.leftover
-    && !xmemcmp(TT.bufs[0], TT.bufs[1], TT.w))
+    && !smemcmp(TT.bufs[0], TT.bufs[1], TT.w))
   {
     if (!TT.star) {
       xputs("*");
diff --git a/toys/posix/ps.c b/toys/posix/ps.c
index 9033cdbd..1fdfc17c 100644
--- a/toys/posix/ps.c
+++ b/toys/posix/ps.c
@@ -845,7 +845,7 @@ static int get_ps(struct dirtree *new)
     off_t temp = 6;
 
     sprintf(buf, "%lld/exe", slot[SLOT_tid]);
-    if (readfileat(fd, buf, buf, &temp) && !xmemcmp(buf, "\177ELF", 4)) {
+    if (readfileat(fd, buf, buf, &temp) && !smemcmp(buf, "\177ELF", 4)) {
       if (buf[4] == 1) slot[SLOT_bits] = 32;
       else if (buf[4] == 2) slot[SLOT_bits] = 64;
     }
diff --git a/toys/posix/tar.c b/toys/posix/tar.c
index aef1397b..8a8601d1 100644
--- a/toys/posix/tar.c
+++ b/toys/posix/tar.c
@@ -990,7 +990,7 @@ void tar_main(void)
       if (len!=512 || !is_tar_header(hdr)) {
         // detect gzip and bzip signatures
         if (SWAP_BE16(*(short *)hdr)==0x1f8b) toys.optflags |= FLAG_z;
-        else if (!xmemcmp(hdr, "BZh", 3)) toys.optflags |= FLAG_j;
+        else if (!smemcmp(hdr, "BZh", 3)) toys.optflags |= FLAG_j;
         else if (peek_be(hdr, 7) == 0xfd377a585a0000UL) toys.optflags |= FLAG_J;
         else error_exit("Not tar");