From: Andrew Gregory <[email protected]> The _alpm_filelist_resolve function takes a filelist and creates a list with any symlinks in directory paths resolved.
Signed-off-by: Allan McRae <[email protected]> --- 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 <limits.h> #include <string.h> +#include <sys/stat.h> /* 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
