From: Andrew Gregory
The _alpm_filelist_resolve function takes a filelist and creates
a list with any symlinks in directory paths resolved.
Signed-off-by: Allan McRae
---
lib/libalpm/filelist.c | 156 +++++++++++++++++++++++++++++++++++++++++++++++++
lib/libalpm/filelist.h | 2 +
2 files changed, 158 insertions(+)
diff --git a/lib/libalpm/filelist.c b/lib/libalpm/filelist.c
index 1928056..d32a3e5 100644
--- a/lib/libalpm/filelist.c
+++ b/lib/libalpm/filelist.c
@@ -17,10 +17,166 @@
* along with this program. If not, see http://www.gnu.org/licenses/.
*/
+#include
#include
+#include
/* libalpm */
#include "filelist.h"
+#include "util.h"
+
+/** Helper function for comparing strings when sorting */
+static int _strcmp(const void *s1, const void *s2)
+{
+ return strcmp(*(char **)s1, *(char **)s2);
+}
+
+/**
+ * @brief Resolves a symlink and its children.
+ *
+ * @attention Pre-condition: files must be sorted!
+ *
+ * @param files filelist to resolve
+ * @param i index in files to start processing
+ * @param path absolute path for the symlink being resolved
+ * @param root_len length of the root portion of path
+ * @param resolving is file \i in \files a symlink that needs to be resolved
+ *
+ * @return the index of the last file resolved
+ */
+size_t _alpm_filelist_resolve_link(
+ alpm_filelist_t *files, size_t i, char *path, size_t root_len, int resolving)
+{
+ struct stat sbuf;
+ const char *causal_dir; /* symlink being resolved */
+ char *filename_r; /* resolved filename */
+ size_t causal_dir_len = 0, causal_dir_r_len = 0;
+
+ if(resolving) {
+ /* deal with the symlink being resolved */
+ filename_r = malloc(PATH_MAX);
+ causal_dir = files->files[i].name;
+ causal_dir_len = strlen(causal_dir);
+ if(realpath(path, filename_r) == NULL) {
+ files->resolved_path[i] = strdup(causal_dir);
+ return i;
+ }
+ causal_dir_r_len = strlen(filename_r + root_len) + 1;
+ if(causal_dir_r_len >= PATH_MAX) {
+ files->resolved_path[i] = strdup(causal_dir);
+ return i;
+ }
+ /* remove root_r from filename_r */
+ memmove(filename_r, filename_r + root_len, causal_dir_r_len + 1);
+ strcpy(filename_r + causal_dir_r_len - 1, "/");
+ files->resolved_path[i] = strdup(filename_r);
+ i++;
+ }
+
+ for(; i < files->count && (!resolving ||
+ strncmp(files->files[i].name, causal_dir, causal_dir_len) == 0); i++) {
+ char *filename = files->files[i].name;
+ size_t f_len = strlen(filename);
+
+ if(resolving) {
+ if(f_len + causal_dir_r_len - causal_dir_len > PATH_MAX) {
+ files->resolved_path[i] = strdup(filename);
+ continue;
+ }
+
+ strcpy(filename_r + causal_dir_r_len, filename + causal_dir_len);
+
+ if(root_len + causal_dir_r_len + f_len - causal_dir_len > PATH_MAX) {
+ /* absolute path is too long */
+ files->resolved_path[i] = strdup(filename_r);
+ continue;
+ }
+ } else {
+ filename_r = filename;
+ }
+
+ /* deal with files and paths too long to resolve*/
+ if(filename[f_len-1] != '/') {
+ files->resolved_path[i] = strdup(filename_r);
+ continue;
+ }
+
+ /* construct absolute path and stat() */
+ strcpy(path + root_len, filename_r);
+ int exists = !_alpm_lstat(path, &sbuf);
+
+ /* deal with symlinks */
+ if(exists && S_ISLNK(sbuf.st_mode)) {
+ i = _alpm_filelist_resolve_link(files, i, path, root_len, 1);
+ continue;
+ }
+
+ /* deal with normal directories */
+ files->resolved_path[i] = strdup(filename_r);
+
+ /* deal with children of non-existent directories to reduce lstat() calls */
+ if (!exists) {
+ char *f;
+ i++;
+ while(i < files->count && strncmp(files->files[i].name, filename, f_len) == 0) {
+ f = files->files[i].name;
+ if(resolving && strlen(f + causal_dir_len) + causal_dir_r_len <= PATH_MAX) {
+ strcpy(filename_r + causal_dir_r_len, f + causal_dir_len);
+ files->resolved_path[i] = strdup(filename_r);
+ } else {
+ files->resolved_path[i] = strdup(f);
+ }
+ i++;
+ }
+ i--;
+ }
+ }
+
+ if(resolving) {
+ free(filename_r);
+ }
+
+ return i-1;
+}
+
+/**
+ * @brief Takes a file list and resolves all directory paths according to filesystem
+ *
+ * @attention Pre-condition: files must be sorted!
+ *
+ * @note A symlink and directory at the same path in two difference packages
+ * causes a conflict so the filepath can not change as packages get installed
+ *
+ * @param handle the context handle
+ * @param files list of files to resolve
+ */
+void _alpm_filelist_resolve(alpm_handle_t *handle, alpm_filelist_t *files)
+{
+ char path[PATH_MAX];
+ size_t root_len;
+
+ if(!files || files->resolved_path) {
+ return;
+ }
+
+ MALLOC(files->resolved_path, files->count * sizeof(char*), return);
+ memset(files->resolved_path, 0, files->count);
+
+ /* not much point in going on if we can't even resolve root */
+ if(realpath(handle->root, path) == NULL){
+ return;
+ }
+ root_len = strlen(path) + 1;
+ if(root_len >= PATH_MAX) {
+ return;
+ }
+ strcpy(path + root_len - 1, "/");
+
+ _alpm_filelist_resolve_link(files, 0, path, root_len, 0);
+
+ qsort(files->resolved_path, files->count, sizeof(char *), _strcmp);
+}
+
/* Returns the difference of the provided two lists of files.
* Pre-condition: both lists are sorted!
diff --git a/lib/libalpm/filelist.h b/lib/libalpm/filelist.h
index 2d5cbc0..3152b9d 100644
--- a/lib/libalpm/filelist.h
+++ b/lib/libalpm/filelist.h
@@ -21,6 +21,8 @@
#include "alpm.h"
+size_t _alpm_filelist_resolve_link(alpm_filelist_t *files, size_t i, char *path, size_t root_len, int resolving);
+void _alpm_filelist_resolve(alpm_handle_t *handle, alpm_filelist_t *files);
alpm_list_t *_alpm_filelist_difference(alpm_filelist_t *filesA,
alpm_filelist_t *filesB);
--
1.7.11.3