Richard W.M. Jones
2010-May-13 09:26 UTC
[Libguestfs] [PATCH] Improve errors from tar-in/tgz-in commands (RHBZ#591155 RHBZ#591250).
-- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming blog: http://rwmj.wordpress.com Fedora now supports 80 OCaml packages (the OPEN alternative to F#) http://cocan.org/getting_started_with_ocaml_on_red_hat_and_fedora -------------- next part -------------->From 29f37dd36c836974d5db53d6f26571f7708b3172 Mon Sep 17 00:00:00 2001From: Richard Jones <rjones at redhat.com> Date: Thu, 13 May 2010 09:56:27 +0100 Subject: [PATCH 2/2] Improve errors from tar-in/tgz-in commands (RHBZ#591155 RHBZ#591250). This commit improves the error messages from the tar-in, tgz-in (etc) commands by capturing the stderr from the tar command in a file and sending that back in the error message. The method used for the error file is primitive, and there is a case for a more generic error file mechanism, but this will do for now. Sample error messages after this change: $ virt-tar -u /tmp/test1.img /tmp/not.tar / tar_in: tar subcommand failed on directory: /: tar: This does not look like a tar archive tar: Skipping to next header tar: Exiting with failure status due to previous errors at /home/rjones/d/libguestfs/tools/virt-tar line 247. $ virt-tar -u /tmp/test1.img /tmp/test.tar / tar_in: tar subcommand failed on directory: /: tar: access.log: Cannot open: Read-only file system tar: Exiting with failure status due to previous errors at /home/rjones/d/libguestfs/tools/virt-tar line 247. --- daemon/.gitignore | 1 + daemon/m4/gnulib-cache.m4 | 3 +- daemon/tar.c | 49 +++++++++++++++++++++++++++++++++++++++----- 3 files changed, 46 insertions(+), 7 deletions(-) diff --git a/daemon/.gitignore b/daemon/.gitignore index 130acb1..440470e 100644 --- a/daemon/.gitignore +++ b/daemon/.gitignore @@ -100,6 +100,7 @@ m4/printf.m4 m4/priv-set.m4 m4/rawmemchr.m4 m4/readlink.m4 +m4/read-file.m4 m4/realloc.m4 m4/rmdir.m4 m4/safe-read.m4 diff --git a/daemon/m4/gnulib-cache.m4 b/daemon/m4/gnulib-cache.m4 index 91c6ac2..f026cb3 100644 --- a/daemon/m4/gnulib-cache.m4 +++ b/daemon/m4/gnulib-cache.m4 @@ -15,7 +15,7 @@ # Specification in the form of a command-line invocation: -# gnulib-tool --import --dir=. --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --with-tests --no-libtool --macro-prefix=gl byteswap c-ctype connect fsusage futimens getaddrinfo getline glob hash ignore-value manywarnings mkdtemp netdb openat perror pread readlink select sleep socket strchrnul strndup symlinkat sys_select sys_wait vasprintf warnings +# gnulib-tool --import --dir=. --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --with-tests --no-libtool --macro-prefix=gl byteswap c-ctype connect error fsusage futimens getaddrinfo getline glob hash ignore-value manywarnings mkdtemp netdb openat perror pread read-file readlink select sleep socket strchrnul strndup symlinkat sys_select sys_wait vasprintf warnings # Specification in the form of a few gnulib-tool.m4 macro invocations: gl_LOCAL_DIR([]) @@ -37,6 +37,7 @@ gl_MODULES([ openat perror pread + read-file readlink select sleep diff --git a/daemon/tar.c b/daemon/tar.c index 1e9698c..4c691bd 100644 --- a/daemon/tar.c +++ b/daemon/tar.c @@ -23,10 +23,40 @@ #include <string.h> #include <fcntl.h> +#include "read-file.h" + #include "../src/guestfs_protocol.h" #include "daemon.h" #include "actions.h" +/* Redirect errors from the tar command to the error file, then + * provide functions for reading it in. We overwrite the file each + * time, and since it's small and stored on the appliance we don't + * bother to delete it. + */ +static const char *error_file = "/tmp/error"; + +static char * +read_error_file (void) +{ + size_t len; + char *str = read_file (error_file, &len); + if (str == NULL) { + str = strdup ("(no error)"); + if (str == NULL) { + perror ("strdup"); + exit (EXIT_FAILURE); + } + len = strlen (str); + } + + /* Remove trailing \n character if any. */ + if (len > 0 && str[len-1] == '\n') + str[--len] = '\0'; + + return str; /* caller frees */ +} + static int write_cb (void *fd_ptr, const void *buf, size_t len) { @@ -43,8 +73,8 @@ do_tXz_in (const char *dir, const char *filter) char *cmd; /* "tar -C /sysroot%s -xf -" but we have to quote the dir. */ - if (asprintf_nowarn (&cmd, "tar -C %R -%sxf -", - dir, filter) == -1) { + if (asprintf_nowarn (&cmd, "tar -C %R -xf - 2> %s", + dir, filter, error_file) == -1) { err = errno; r = cancel_receive (); errno = err; @@ -73,8 +103,11 @@ do_tXz_in (const char *dir, const char *filter) r = receive_file (write_cb, &fd); if (r == -1) { /* write error */ - if (cancel_receive () != -2) - reply_with_error ("write error on directory: %s", dir); + if (cancel_receive () != -2) { + char *errstr = read_error_file (); + reply_with_error ("write error on directory: %s: %s", dir, errstr); + free (errstr); + } pclose (fp); return -1; } @@ -87,8 +120,12 @@ do_tXz_in (const char *dir, const char *filter) if (pclose (fp) != 0) { if (r == -1) /* if r == 0, file transfer ended already */ r = cancel_receive (); - if (r != -2) - reply_with_error ("tar subcommand failed on directory: %s", dir); + if (r != -2) { + char *errstr = read_error_file (); + reply_with_error ("tar subcommand failed on directory: %s: %s", + dir, errstr); + free (errstr); + } return -1; } -- 1.6.6.1
Richard W.M. Jones
2010-May-13 10:31 UTC
[Libguestfs] [PATCH] Improve errors from tar-in/tgz-in commands (RHBZ#591155 RHBZ#591250).
On Thu, May 13, 2010 at 10:26:19AM +0100, Richard W.M. Jones wrote:> - if (asprintf_nowarn (&cmd, "tar -C %R -%sxf -", > - dir, filter) == -1) { > + if (asprintf_nowarn (&cmd, "tar -C %R -xf - 2> %s", > + dir, filter, error_file) == -1) {The patch got mangled here somehow. This should read: - if (asprintf_nowarn (&cmd, "tar -C %R -%sxf -", - dir, filter) == -1) { + if (asprintf_nowarn (&cmd, "tar -C %R -%sxf - 2> %s", + dir, filter, error_file) == -1) { Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones New in Fedora 11: Fedora Windows cross-compiler. Compile Windows programs, test, and build Windows installers. Over 70 libraries supprt'd http://fedoraproject.org/wiki/MinGW http://www.annexia.org/fedora_mingw
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