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[src/trunk]: src/bin/pax pax: don't overwrite destination if -r -w copy fails



details:   https://anonhg.NetBSD.org/src/rev/6d53b1c30c67
branches:  trunk
changeset: 376056:6d53b1c30c67
user:      lukem <lukem%NetBSD.org@localhost>
date:      Sun May 28 21:42:40 2023 +0000

description:
pax: don't overwrite destination if -r -w copy fails

Add more error handling to pax -r -w so that any failure
during the copy to the temporary file (including a failed flush)
prevents any existing destination file from being replaced
with the partial (including possibly empty) temporary file.
The partial temporary file is removed.  pax still exists non-zero.

Thanks to Michael van Elst (mlelstv@) for the analysis
of the problem in the PR.

Should fix PR misc/33753.

diffstat:

 bin/pax/ar_subs.c   |  14 ++++++++----
 bin/pax/buf_subs.c  |  45 ++++++++++++++++++++++++++++++-------------
 bin/pax/extern.h    |   7 +++--
 bin/pax/file_subs.c |  54 ++++++++++++++++++++++++++++++++++++++++++++--------
 4 files changed, 89 insertions(+), 31 deletions(-)

diffs (294 lines):

diff -r 7afeef74106a -r 6d53b1c30c67 bin/pax/ar_subs.c
--- a/bin/pax/ar_subs.c Sun May 28 17:01:46 2023 +0000
+++ b/bin/pax/ar_subs.c Sun May 28 21:42:40 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ar_subs.c,v 1.57 2021/12/05 02:52:17 msaitoh Exp $     */
+/*     $NetBSD: ar_subs.c,v 1.58 2023/05/28 21:42:40 lukem Exp $       */
 
 /*-
  * Copyright (c) 1992 Keith Muller.
@@ -42,7 +42,7 @@
 #if 0
 static char sccsid[] = "@(#)ar_subs.c  8.2 (Berkeley) 4/18/94";
 #else
-__RCSID("$NetBSD: ar_subs.c,v 1.57 2021/12/05 02:52:17 msaitoh Exp $");
+__RCSID("$NetBSD: ar_subs.c,v 1.58 2023/05/28 21:42:40 lukem Exp $");
 #endif
 #endif /* not lint */
 
@@ -1131,10 +1131,14 @@ copy(void)
                }
 
                /*
-                * copy source file data to the destination file
+                * copy source file data to the destination file.
+                * if there was a failure, remove the temporary file
+                * and leave any existing destination file unmodified.
                 */
-               cp_file(arcn, fdsrc, fddest);
-               file_close(arcn, fddest);
+               if (cp_file(arcn, fdsrc, fddest) < 0)
+                       file_cleanup(arcn, fddest);
+               else
+                       file_close(arcn, fddest);
                rdfile_close(arcn, &fdsrc);
 
                if (vflag && vfpart) {
diff -r 7afeef74106a -r 6d53b1c30c67 bin/pax/buf_subs.c
--- a/bin/pax/buf_subs.c        Sun May 28 17:01:46 2023 +0000
+++ b/bin/pax/buf_subs.c        Sun May 28 21:42:40 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: buf_subs.c,v 1.30 2022/05/28 10:36:21 andvar Exp $     */
+/*     $NetBSD: buf_subs.c,v 1.31 2023/05/28 21:42:40 lukem Exp $      */
 
 /*-
  * Copyright (c) 1992 Keith Muller.
@@ -42,7 +42,7 @@
 #if 0
 static char sccsid[] = "@(#)buf_subs.c 8.2 (Berkeley) 4/18/94";
 #else
-__RCSID("$NetBSD: buf_subs.c,v 1.30 2022/05/28 10:36:21 andvar Exp $");
+__RCSID("$NetBSD: buf_subs.c,v 1.31 2023/05/28 21:42:40 lukem Exp $");
 #endif
 #endif /* not lint */
 
@@ -745,8 +745,11 @@ rd_wrfile(ARCHD *arcn, int ofd, off_t *l
         * written. just closing with the file offset moved forward may not put
         * a hole at the end of the file.
         */
-       if (ofd >= 0 && isem && (arcn->sb.st_size > 0L))
-               file_flush(ofd, fnm, isem);
+       if (ofd >= 0 && isem && (arcn->sb.st_size > 0L)) {
+               if (file_flush(ofd, fnm, isem) < 0) {
+                       /* write flush errors are not an error here */;
+               }
+       }
 
        /*
         * if we failed from archive read, we do not want to skip
@@ -758,9 +761,11 @@ rd_wrfile(ARCHD *arcn, int ofd, off_t *l
         * some formats record a crc on file data. If so, then we compare the
         * calculated crc to the crc stored in the archive
         */
-       if (docrc && (size == 0L) && (arcn->crc != crc))
+       if (docrc && (size == 0L) && (arcn->crc != crc)) {
                tty_warn(1,"Actual crc does not match expected crc %s",
                    arcn->name);
+               /* crc warning is not an error */
+       }
        return 0;
 }
 
@@ -769,9 +774,11 @@ rd_wrfile(ARCHD *arcn, int ofd, off_t *l
  *     copy the contents of one file to another. used during -rw phase of pax
  *     just as in rd_wrfile() we use a special write function to write the
  *     destination file so we can properly copy files with holes.
+ * Return:
+ *     0 if ok, -1 if any error.
  */
 
-void
+int
 cp_file(ARCHD *arcn, int fd1, int fd2)
 {
        int cnt;
@@ -783,6 +790,7 @@ cp_file(ARCHD *arcn, int fd1, int fd2)
        int rem;
        int sz = MINFBSZ;
        struct stat sb, origsb;
+       int rv = 0;
 
        /*
         * check for holes in the source file. If none, we will use regular
@@ -797,8 +805,10 @@ cp_file(ARCHD *arcn, int fd1, int fd2)
         * if Mflag is set, use the actual mtime instead.
         */
        origsb = arcn->sb;
-       if (Mflag && (fstat(fd1, &origsb) < 0))
+       if (Mflag && (fstat(fd1, &origsb) < 0)) {
                syswarn(1, errno, "Failed stat on %s", arcn->org_name);
+               rv = -1;
+       }
 
        /*
         * pass the blocksize of the file being written to the write routine,
@@ -830,17 +840,22 @@ cp_file(ARCHD *arcn, int fd1, int fd2)
        /*
         * check to make sure the copy is valid.
         */
-       if (res < 0)
+       if (res < 0) {
                syswarn(1, errno, "Failed write during copy of %s to %s",
                        arcn->org_name, arcn->name);
-       else if (cpcnt != arcn->sb.st_size)
+               rv = -1;
+       } else if (cpcnt != arcn->sb.st_size) {
                tty_warn(1, "File %s changed size during copy to %s",
                        arcn->org_name, arcn->name);
-       else if (fstat(fd1, &sb) < 0)
+               rv = -1;
+       } else if (fstat(fd1, &sb) < 0) {
                syswarn(1, errno, "Failed stat of %s", arcn->org_name);
-       else if (origsb.st_mtime != sb.st_mtime)
+               rv = -1;
+       } else if (origsb.st_mtime != sb.st_mtime) {
                tty_warn(1, "File %s was modified during copy to %s",
                        arcn->org_name, arcn->name);
+               rv = -1;
+       }
 
        /*
         * if the last block has a file hole (all zero), we must make sure this
@@ -848,9 +863,11 @@ cp_file(ARCHD *arcn, int fd1, int fd2)
         * written. just closing with the file offset moved forward may not put
         * a hole at the end of the file.
         */
-       if (!no_hole && isem && (arcn->sb.st_size > 0L))
-               file_flush(fd2, fnm, isem);
-       return;
+       if (!no_hole && isem && (arcn->sb.st_size > 0L)) {
+               if (file_flush(fd2, fnm, isem) < 0)
+                       rv = -1;
+       }
+       return rv;
 }
 
 /*
diff -r 7afeef74106a -r 6d53b1c30c67 bin/pax/extern.h
--- a/bin/pax/extern.h  Sun May 28 17:01:46 2023 +0000
+++ b/bin/pax/extern.h  Sun May 28 21:42:40 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: extern.h,v 1.60 2020/04/03 16:13:32 joerg Exp $        */
+/*     $NetBSD: extern.h,v 1.61 2023/05/28 21:42:40 lukem Exp $        */
 
 /*-
  * Copyright (c) 1992 Keith Muller.
@@ -115,7 +115,7 @@ int rd_wrbuf(char *, int);
 int wr_skip(off_t);
 int wr_rdfile(ARCHD *, int, off_t *);
 int rd_wrfile(ARCHD *, int, off_t *);
-void cp_file(ARCHD *, int, int);
+int cp_file(ARCHD *, int, int);
 int buf_fill(void);
 int buf_flush(int);
 
@@ -150,6 +150,7 @@ extern char *gnu_name_string, *gnu_link_
 extern size_t gnu_name_length, gnu_link_length;
 extern char *xtmp_name;
 int file_creat(ARCHD *, int);
+void file_cleanup(ARCHD *, int);
 void file_close(ARCHD *, int);
 int lnk_creat(ARCHD *, int *);
 int cross_lnk(ARCHD *);
@@ -162,7 +163,7 @@ int set_ids(char *, uid_t, gid_t);
 void set_pmode(char *, mode_t);
 void set_chflags(char *fnm, u_int32_t flags);
 int file_write(int, char *, int, int *, int *, int, char *);
-void file_flush(int, char *, int);
+int file_flush(int, char *, int);
 void rdfile_close(ARCHD *, int *);
 int set_crc(ARCHD *, int);
 
diff -r 7afeef74106a -r 6d53b1c30c67 bin/pax/file_subs.c
--- a/bin/pax/file_subs.c       Sun May 28 17:01:46 2023 +0000
+++ b/bin/pax/file_subs.c       Sun May 28 21:42:40 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: file_subs.c,v 1.64 2019/03/20 03:13:39 gutteridge Exp $        */
+/*     $NetBSD: file_subs.c,v 1.65 2023/05/28 21:42:40 lukem Exp $     */
 
 /*-
  * Copyright (c) 1992 Keith Muller.
@@ -42,7 +42,7 @@
 #if 0
 static char sccsid[] = "@(#)file_subs.c        8.1 (Berkeley) 5/31/93";
 #else
-__RCSID("$NetBSD: file_subs.c,v 1.64 2019/03/20 03:13:39 gutteridge Exp $");
+__RCSID("$NetBSD: file_subs.c,v 1.65 2023/05/28 21:42:40 lukem Exp $");
 #endif
 #endif /* not lint */
 
@@ -179,11 +179,43 @@ file_creat(ARCHD *arcn, int write_to_har
 }
 
 /*
+ * file_cleanup()
+ *     Close file descriptor to a file just created by pax.
+ *     Unlinks any temporary file.
+ */
+
+void
+file_cleanup(ARCHD *arcn, int fd)
+{
+       char *tmp_name;
+
+       if (fd < 0)
+               return;
+
+       tmp_name = (arcn->tmp_name != NULL) ? arcn->tmp_name : arcn->name;
+
+       if (close(fd) < 0)
+               syswarn(0, errno, "Cannot close file descriptor on %s",
+                   tmp_name);
+
+       /* No temporary file to cleanup? */
+       if (arcn->tmp_name == NULL)
+               return;
+
+       /* Cleanup the temporary file. */
+       if (unlink(arcn->tmp_name) < 0) {
+               syswarn(0, errno, "Cannot unlink %s", arcn->tmp_name);
+       }
+
+       free(arcn->tmp_name);
+       arcn->tmp_name = NULL;
+       xtmp_name = NULL;
+}
+
+/*
  * file_close()
  *     Close file descriptor to a file just created by pax. Sets modes,
  *     ownership and times as required.
- * Return:
- *     0 for success, -1 for failure
  */
 
 void
@@ -1039,9 +1071,11 @@ file_write(int fd, char *str, int cnt, i
  *     when the last file block in a file is zero, many file systems will not
  *     let us create a hole at the end. To get the last block with zeros, we
  *     write the last BYTE with a zero (back up one byte and write a zero).
+ * Return:
+ *     0 if was able to flush the file, -1 otherwise
  */
 
-void
+int
 file_flush(int fd, char *fname, int isempt)
 {
        static char blnk[] = "\0";
@@ -1051,19 +1085,21 @@ file_flush(int fd, char *fname, int isem
         * filled with all zeros.
         */
        if (!isempt)
-               return;
+               return 0;
 
        /*
         * move back one byte and write a zero
         */
        if (lseek(fd, (off_t)-1, SEEK_CUR) < 0) {
                syswarn(1, errno, "Failed seek on file %s", fname);
-               return;
+               return -1;
        }
 
-       if (write_with_restart(fd, blnk, 1) < 0)
+       if (write_with_restart(fd, blnk, 1) < 0) {
                syswarn(1, errno, "Failed write to file %s", fname);
-       return;
+               return -1;
+       }
+       return 0;
 }
 
 /*



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