Libguestfs - Oct 2012 - [PATCH for discussion] lib: update inspect_list_applications to return app_arch

Here's a partially implemented fix for RHBZ#859949.  Seeing as this is
my first libguestfs patch, I'd like some other eyeballs on it to make
sure I've not done anything completely crazy.

If the rpm case looks ok, I'll update the deb and windows cases
if/where applicable.

(Work in progress)

For now this only works for RPM, the others just return an empty string.
---
 generator/structs.ml |  1 +
 src/inspect-apps.c   | 88 +++++++++++++++++++++++++++++-----------------------
 2 files changed, 51 insertions(+), 38 deletions(-)

diff --git a/generator/structs.ml b/generator/structs.ml
index d62fcc5..8ac9fc5 100644
--- a/generator/structs.ml
+++ b/generator/structs.ml
@@ -183,6 +183,7 @@ let structs = [
     "app_epoch", FInt32;
     "app_version", FString;
     "app_release", FString;
+    "app_arch", FString;
     "app_install_path", FString;
     "app_trans_path", FString;
     "app_publisher", FString;
diff --git a/src/inspect-apps.c b/src/inspect-apps.c
index f65c70a..3dbfb5b 100644
--- a/src/inspect-apps.c
+++ b/src/inspect-apps.c
@@ -31,6 +31,7 @@
 #ifdef HAVE_ENDIAN_H
 #include <endian.h>
 #endif
+#include <arpa/inet.h>
 
 #include <pcre.h>
 
@@ -46,7 +47,7 @@ static struct guestfs_application_list *list_applications_rpm
(guestfs_h *g, str
 #endif
 static struct guestfs_application_list *list_applications_deb (guestfs_h *g,
struct inspect_fs *fs);
 static struct guestfs_application_list *list_applications_windows (guestfs_h
*g, struct inspect_fs *fs);
-static void add_application (guestfs_h *g, struct guestfs_application_list *,
const char *name, const char *display_name, int32_t epoch, const char *version,
const char *release, const char *install_path, const char *publisher, const char
*url, const char *description);
+static void add_application (guestfs_h *g, struct guestfs_application_list *,
const char *name, const char *display_name, int32_t epoch, const char *version,
const char *release, const char *arch, const char *install_path, const char
*publisher, const char *url, const char *description);
 static void sort_applications (struct guestfs_application_list *);
 
 /* Unlike the simple inspect-get-* calls, this one assumes that the
@@ -181,6 +182,37 @@ read_rpm_name (guestfs_h *g,
   return 0;
 }
 
+/* tag constants, see rpmtag.h in RPM for complete list */
+#define RPMTAG_VERSION 1001
+#define RPMTAG_RELEASE 1002
+#define RPMTAG_ARCH    1022
+
+static char *
+get_rpm_header_tag (guestfs_h *g, const void *header_start, size_t header_len,
uint32_t tag)
+{
+  uint32_t num_fields, offset;
+  const void *cursor = header_start + 8, *store;
+
+  /* This function parses the RPM header structure to pull out various
+   * tag strings (version, release, arch, etc.).  For more detail on the
+   * header format, see:
+   *
http://www.rpm.org/max-rpm/s1-rpm-file-format-rpm-file-format.html#S2-RPM-FILE-FORMAT-HEADER
+   */
+
+  num_fields = ntohl (*(uint32_t *) header_start);
+  store = header_start + 8 + (16 * num_fields);
+
+  while (cursor < store ){
+    if (ntohl (*(uint32_t *) cursor) == tag){
+      offset = ntohl(*(uint32_t *) (cursor + 8));
+      return safe_strdup(g, store + offset);
+    }
+    cursor += 16;
+  }
+
+  return NULL;
+}
+
 struct read_package_data {
   struct rpm_names_list *list;
   struct guestfs_application_list *apps;
@@ -194,16 +226,13 @@ read_package (guestfs_h *g,
 {
   struct read_package_data *data = datav;
   struct rpm_name nkey, *entry;
-  char *p;
-  size_t len;
-  ssize_t max;
-  char *nul_name_nul, *version, *release;
+  char *version, *release, *arch;
 
   /* This function reads one (key, value) pair from the Packages
    * database.  The key is the link field (see struct rpm_name).  The
-   * value is a long binary string, but we can extract the version
-   * number from it as below.  First we have to look up the link field
-   * in the list of links (which is sorted by link field).
+   * value is a long binary string, but we can extract the header data
+   * from it as below.  First we have to look up the link field in the
+   * list of links (which is sorted by link field).
    */
 
   /* Ignore bogus entries. */
@@ -219,41 +248,23 @@ read_package (guestfs_h *g,
 
   /* We found a matching link entry, so that gives us the application
    * name (entry->name).  Now we can get other data for this
-   * application out of the binary value string.  XXX This is a real
-   * hack.
+   * application out of the binary value string.
    */
 
-  /* Look for \0<name>\0 */
-  len = strlen (entry->name);
-  nul_name_nul = safe_malloc (g, len + 2);
-  nul_name_nul[0] = '\0';
-  memcpy (&nul_name_nul[1], entry->name, len);
-  nul_name_nul[len+1] = '\0';
-  p = memmem (value, valuelen, nul_name_nul, len+2);
-  free (nul_name_nul);
-  if (!p)
-    return 0;
-
-  /* Following that are \0-delimited version and release fields. */
-  p += len + 2; /* Note we have to skip \0 + name + \0. */
-  max = valuelen - (p - (char *) value);
-  if (max < 0)
-    max = 0;
-  version = safe_strndup (g, p, max);
-
-  len = strlen (version);
-  p += len + 1;
-  max = valuelen - (p - (char *) value);
-  if (max < 0)
-    max = 0;
-  release = safe_strndup (g, p, max);
+  version = get_rpm_header_tag(g, value, valuelen, RPMTAG_VERSION);
+  release = get_rpm_header_tag(g, value, valuelen, RPMTAG_RELEASE);
+  arch = get_rpm_header_tag(g, value, valuelen, RPMTAG_ARCH);
 
   /* Add the application and what we know. */
   add_application (g, data->apps, entry->name, "", 0, version,
release,
-                   "", "", "", "");
+                   arch ? arch : "(none)", "",
"", "", "");
 
   free (version);
   free (release);
+  if (arch)
+    /* arch will occasionally be NULL, because some packages
+     * (e.g. "gpgkeys") do not have an arch */
+    free (arch);
 
   return 0;
 }
@@ -378,7 +389,7 @@ list_applications_deb (guestfs_h *g, struct inspect_fs *fs)
     else if (STREQ (line, "")) {
       if (installed_flag && name && version)
         add_application (g, apps, name, "", 0, version, release ? :
"",
-                         "", "", "",
"");
+                         "", "", "",
"", "");
       free (name);
       free (version);
       free (release);
@@ -519,7 +530,7 @@ list_applications_windows_from_path (guestfs_h *g,
 
         add_application (g, apps, name, display_name, 0,
                          version ? : "",
-                         "",
+                         "", "",
                          install_path ? : "",
                          publisher ? : "",
                          url ? : "",
@@ -542,7 +553,7 @@ list_applications_windows_from_path (guestfs_h *g,
 static void
 add_application (guestfs_h *g, struct guestfs_application_list *apps,
                  const char *name, const char *display_name, int32_t epoch,
-                 const char *version, const char *release,
+                 const char *version, const char *release, const char *arch,
                  const char *install_path,
                  const char *publisher, const char *url,
                  const char *description)
@@ -555,6 +566,7 @@ add_application (guestfs_h *g, struct
guestfs_application_list *apps,
   apps->val[apps->len-1].app_epoch = epoch;
   apps->val[apps->len-1].app_version = safe_strdup (g, version);
   apps->val[apps->len-1].app_release = safe_strdup (g, release);
+  apps->val[apps->len-1].app_arch = safe_strdup (g, arch);
   apps->val[apps->len-1].app_install_path = safe_strdup (g,
install_path);
   /* XXX Translated path is not implemented yet. */
   apps->val[apps->len-1].app_trans_path = safe_strdup (g, "");
-- 
1.7.11.4