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201 lines
6.5 KiB
201 lines
6.5 KiB
diff --git a/ChangeLog b/ChangeLog |
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index d46caaa0d..41d6e99d9 100644 |
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--- a/ChangeLog |
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+++ b/ChangeLog |
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@@ -1,3 +1,8 @@ |
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+2020-12-08 16:24 Christos Zoulas <christos@zoulas.com> |
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+ |
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+ * fix multithreaded decompression file descriptor issue |
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+ by using close-on-exec (Denys Vlasenko) |
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+ |
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2020-06-14 20:02 Christos Zoulas <christos@zoulas.com> |
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* release 5.39 |
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diff --git a/configure.ac b/configure.ac |
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index 64c9f42e3..521dc12db 100644 |
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--- a/configure.ac |
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+++ b/configure.ac |
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@@ -166,7 +166,7 @@ else |
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fi]) |
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dnl Checks for functions |
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-AC_CHECK_FUNCS(strndup mkstemp mkostemp utimes utime wcwidth strtof newlocale uselocale freelocale memmem) |
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+AC_CHECK_FUNCS(strndup mkstemp mkostemp utimes utime wcwidth strtof newlocale uselocale freelocale memmem pipe2) |
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dnl Provide implementation of some required functions if necessary |
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AC_REPLACE_FUNCS(getopt_long asprintf vasprintf strlcpy strlcat getline ctime_r asctime_r localtime_r gmtime_r pread strcasestr fmtcheck dprintf) |
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diff --git a/src/compress.c b/src/compress.c |
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index cbc2ce19b..9f65e4fa1 100644 |
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--- a/src/compress.c |
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+++ b/src/compress.c |
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@@ -35,7 +35,7 @@ |
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#include "file.h" |
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#ifndef lint |
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-FILE_RCSID("@(#)$File: compress.c,v 1.127 2020/05/31 00:11:06 christos Exp $") |
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+FILE_RCSID("@(#)$File: compress.c,v 1.129 2020/12/08 21:26:00 christos Exp $") |
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#endif |
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#include "magic.h" |
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@@ -844,8 +844,23 @@ uncompressbuf(int fd, size_t bytes_max, size_t method, const unsigned char *old, |
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for (i = 0; i < __arraycount(fdp); i++) |
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fdp[i][0] = fdp[i][1] = -1; |
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- if ((fd == -1 && pipe(fdp[STDIN_FILENO]) == -1) || |
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- pipe(fdp[STDOUT_FILENO]) == -1 || pipe(fdp[STDERR_FILENO]) == -1) { |
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+ /* |
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+ * There are multithreaded users who run magic_file() |
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+ * from dozens of threads. If two parallel magic_file() calls |
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+ * analyze two large compressed files, both will spawn |
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+ * an uncompressing child here, which writes out uncompressed data. |
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+ * We read some portion, then close the pipe, then waitpid() the child. |
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+ * If uncompressed data is larger, child shound get EPIPE and exit. |
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+ * However, with *parallel* calls OTHER child may unintentionally |
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+ * inherit pipe fds, thus keeping pipe open and making writes in |
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+ * our child block instead of failing with EPIPE! |
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+ * (For the bug to occur, two threads must mutually inherit their pipes, |
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+ * and both must have large outputs. Thus it happens not that often). |
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+ * To avoid this, be sure to create pipes with O_CLOEXEC. |
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+ */ |
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+ if ((fd == -1 && file_pipe_closexec(fdp[STDIN_FILENO]) == -1) || |
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+ file_pipe_closexec(fdp[STDOUT_FILENO]) == -1 || |
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+ file_pipe_closexec(fdp[STDERR_FILENO]) == -1) { |
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closep(fdp[STDIN_FILENO]); |
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closep(fdp[STDOUT_FILENO]); |
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return makeerror(newch, n, "Cannot create pipe, %s", |
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@@ -876,16 +891,20 @@ uncompressbuf(int fd, size_t bytes_max, size_t method, const unsigned char *old, |
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if (fdp[STDIN_FILENO][1] > 2) |
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(void) close(fdp[STDIN_FILENO][1]); |
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} |
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+ file_clear_closexec(STDIN_FILENO); |
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+ |
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///FIXME: if one of the fdp[i][j] is 0 or 1, this can bomb spectacularly |
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if (copydesc(STDOUT_FILENO, fdp[STDOUT_FILENO][1])) |
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(void) close(fdp[STDOUT_FILENO][1]); |
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if (fdp[STDOUT_FILENO][0] > 2) |
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(void) close(fdp[STDOUT_FILENO][0]); |
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+ file_clear_closexec(STDOUT_FILENO); |
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if (copydesc(STDERR_FILENO, fdp[STDERR_FILENO][1])) |
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(void) close(fdp[STDERR_FILENO][1]); |
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if (fdp[STDERR_FILENO][0] > 2) |
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(void) close(fdp[STDERR_FILENO][0]); |
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+ file_clear_closexec(STDERR_FILENO); |
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(void)execvp(compr[method].argv[0], |
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RCAST(char *const *, RCAST(intptr_t, compr[method].argv))); |
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diff --git a/src/file.h b/src/file.h |
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index f00e8010b..6c3900479 100644 |
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--- a/src/file.h |
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+++ b/src/file.h |
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@@ -27,7 +27,7 @@ |
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*/ |
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/* |
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* file.h - definitions for file(1) program |
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- * @(#)$File: file.h,v 1.220 2020/06/08 17:38:27 christos Exp $ |
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+ * @(#)$File: file.h,v 1.223 2020/12/08 21:26:00 christos Exp $ |
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*/ |
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#ifndef __file_h__ |
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@@ -143,6 +143,14 @@ |
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#define MAX(a,b) (((a) > (b)) ? (a) : (b)) |
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#endif |
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+#ifndef O_CLOEXEC |
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+# define O_CLOEXEC 0 |
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+#endif |
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+ |
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+#ifndef FD_CLOEXEC |
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+# define FD_CLOEXEC 1 |
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+#endif |
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+ |
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#define FILE_BADSIZE CAST(size_t, ~0ul) |
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#define MAXDESC 64 /* max len of text description/MIME type */ |
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#define MAXMIME 80 /* max len of text MIME type */ |
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@@ -540,6 +548,8 @@ protected char * file_printable(char *, size_t, const char *, size_t); |
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protected int file_os2_apptype(struct magic_set *, const char *, const void *, |
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size_t); |
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#endif /* __EMX__ */ |
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+protected int file_pipe_closexec(int *); |
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+protected int file_clear_closexec(int); |
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protected void buffer_init(struct buffer *, int, const struct stat *, |
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const void *, size_t); |
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diff --git a/src/funcs.c b/src/funcs.c |
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index ecbfa28c5..bcf9ddaae 100644 |
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--- a/src/funcs.c |
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+++ b/src/funcs.c |
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@@ -27,7 +27,7 @@ |
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#include "file.h" |
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#ifndef lint |
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-FILE_RCSID("@(#)$File: funcs.c,v 1.115 2020/02/20 15:50:20 christos Exp $") |
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+FILE_RCSID("@(#)$File: funcs.c,v 1.118 2020/12/08 21:26:00 christos Exp $") |
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#endif /* lint */ |
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#include "magic.h" |
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@@ -36,6 +36,9 @@ FILE_RCSID("@(#)$File: funcs.c,v 1.117 2020/06/25 16:52:48 christos Exp $") |
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#include <stdlib.h> |
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#include <string.h> |
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#include <ctype.h> |
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+#ifdef HAVE_UNISTD_H |
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+#include <unistd.h> /* for pipe2() */ |
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+#endif |
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#if defined(HAVE_WCHAR_H) |
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#include <wchar.h> |
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#endif |
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@@ -784,3 +787,22 @@ file_print_guid(char *str, size_t len, const uint64_t *guid) |
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g->data4[2], g->data4[3], g->data4[4], g->data4[5], |
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g->data4[6], g->data4[7]); |
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} |
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+ |
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+protected int |
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+file_pipe_closexec(int *fds) |
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+{ |
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+#ifdef HAVE_PIPE2 |
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+ return pipe2(fds, O_CLOEXEC); |
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+#else |
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+ if (pipe(fds) == -1) |
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+ return -1; |
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+ (void)fcntl(fds[0], F_SETFD, FD_CLOEXEC); |
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+ (void)fcntl(fds[1], F_SETFD, FD_CLOEXEC); |
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+ return 0; |
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+#endif |
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+} |
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+ |
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+protected int |
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+file_clear_closexec(int fd) { |
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+ return fcntl(fd, F_SETFD, 0); |
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+} |
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diff --git a/src/magic.c b/src/magic.c |
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index 17a7077d8..89f4e16c0 100644 |
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--- a/src/magic.c |
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+++ b/src/magic.c |
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@@ -33,7 +33,7 @@ |
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#include "file.h" |
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#ifndef lint |
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-FILE_RCSID("@(#)$File: magic.c,v 1.112 2020/06/08 19:44:10 christos Exp $") |
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+FILE_RCSID("@(#)$File: magic.c,v 1.113 2020/12/08 21:26:00 christos Exp $") |
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#endif /* lint */ |
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#include "magic.h" |
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@@ -436,7 +436,7 @@ file_or_fd(struct magic_set *ms, const char *inname, int fd) |
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_setmode(STDIN_FILENO, O_BINARY); |
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#endif |
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if (inname != NULL) { |
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- int flags = O_RDONLY|O_BINARY|O_NONBLOCK; |
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+ int flags = O_RDONLY|O_BINARY|O_NONBLOCK|O_CLOEXEC; |
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errno = 0; |
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if ((fd = open(inname, flags)) < 0) { |
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okstat = stat(inname, &sb) == 0; |
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@@ -460,6 +460,9 @@ file_or_fd(struct magic_set *ms, const char *inname, int fd) |
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rv = 0; |
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goto done; |
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} |
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+#if O_CLOEXEC == 0 |
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+ (void)fcntl(fd, F_SETFD, FD_CLOEXEC); |
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+#endif |
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} |
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if (fd != -1) {
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