libalpm: check for duplicate filenames

This partially fixes FS#67850

It fixes the case for -S'ing packages but not -U'ing urls.

pacman -S a/a b/b
resolving dependencies...
error: packages a and b have the same filename: a-1-1-any.pkg.tar.zst
error: failed to prepare transaction (duplicate filename)

Signed-off-by: Allan McRae <allan@archlinux.org>

3 files changed, 23 insertions, 0 deletions

diff --git a/lib/libalpm/alpm.h b/lib/libalpm/alpm.h
index aef86d78..c4acc062 100644
--- a/lib/libalpm/alpm.h
+++ b/lib/libalpm/alpm.h
@@ -257,6 +257,8 @@ typedef enum _alpm_errno_t {
 	ALPM_ERR_TRANS_NULL,
 	/** Duplicate target in transaction */
 	ALPM_ERR_TRANS_DUP_TARGET,
+	/** Duplicate filename in transaction */
+	ALPM_ERR_TRANS_DUP_FILENAME,
 	/** A transaction has not been initialized */
 	ALPM_ERR_TRANS_NOT_INITIALIZED,
 	/** Transaction has not been prepared */
diff --git a/lib/libalpm/error.c b/lib/libalpm/error.c
index c6f19599..c06d091a 100644
--- a/lib/libalpm/error.c
+++ b/lib/libalpm/error.c
@@ -90,6 +90,8 @@ const char SYMEXPORT *alpm_strerror(alpm_errno_t err)
 			return _("transaction not initialized");
 		case ALPM_ERR_TRANS_DUP_TARGET:
 			return _("duplicate target");
+		case ALPM_ERR_TRANS_DUP_FILENAME:
+			return _("duplicate filename");
 		case ALPM_ERR_TRANS_NOT_INITIALIZED:
 			return _("transaction not initialized");
 		case ALPM_ERR_TRANS_NOT_PREPARED:
diff --git a/lib/libalpm/sync.c b/lib/libalpm/sync.c
index bdfab635..7ef558c4 100644
--- a/lib/libalpm/sync.c
+++ b/lib/libalpm/sync.c
@@ -464,6 +464,25 @@ int _alpm_sync_prepare(alpm_handle_t *handle, alpm_list_t **data)
 			}
 		}
 
+		/* Ensure two packages don't have the same filename */
+		for(i = resolved; i; i = i->next) {
+			alpm_pkg_t *pkg1 = i->data;
+			for(j = i->next; j; j = j->next) {
+				alpm_pkg_t *pkg2 = j->data;
+				if(strcmp(pkg1->filename, pkg2->filename) == 0) {
+					alpm_list_free(resolved);
+					ret = -1;
+					handle->pm_errno = ALPM_ERR_TRANS_DUP_FILENAME;
+					_alpm_log(handle, ALPM_LOG_ERROR, _("packages %s and %s have the same filename: %s\n"),
+						pkg1->name, pkg2->name, pkg1->filename);
+				}
+			}
+		}
+
+		if(ret != 0) {
+			goto cleanup;
+		}
+
 		/* Set DEPEND reason for pulled packages */
 		for(i = resolved; i; i = i->next) {
 			alpm_pkg_t *pkg = i->data;