thodg/got

diff --git a/include/got_error.h b/include/got_error.h
index 785766a..afb23f6 100644
--- a/include/got_error.h
+++ b/include/got_error.h
@@ -190,6 +190,13 @@ const struct got_error *got_error_msg(int, const char *);
 const struct got_error *got_error_from_errno(void);
 
 /*
+ * Get a statically allocated error object with code GOT_ERR_ERRNO
+ * and an error message obtained from strerror(3), prefixed with a
+ * string.
+ */
+const struct got_error *got_error_prefix_errno(const char *);
+
+/*
  * Set errno to the specified error code and return a statically
  * allocated error object with code GOT_ERR_ERRNO and an error
  * message obtained from strerror(3).
diff --git a/lib/error.c b/lib/error.c
index 8ac3f42..bb4d6fe 100644
--- a/lib/error.c
+++ b/lib/error.c
@@ -23,6 +23,7 @@
 #include <sha1.h>
 #include <zlib.h>
 #include <uuid.h>
+#include <sys/param.h>
 
 #include "got_error.h"
 #include "got_object.h"
@@ -77,6 +78,20 @@ got_error_from_errno(void)
 }
 
 const struct got_error *
+got_error_prefix_errno(const char *prefix)
+{
+	static struct got_error err;
+	static char err_msg[MAXPATHLEN + 20];
+
+	snprintf(err_msg, sizeof(err_msg), "%s: %s", prefix,
+	    strerror(errno));
+
+	err.code = GOT_ERR_ERRNO;
+	err.msg = err_msg;
+	return &err;
+}
+
+const struct got_error *
 got_error_set_errno(int code)
 {
 	errno = code;
diff --git a/lib/object.c b/lib/object.c
index 8356628..8c71dc8 100644
--- a/lib/object.c
+++ b/lib/object.c
@@ -118,7 +118,7 @@ got_object_get_path(char **path, struct got_object_id *id,
 	*path = NULL;
 
 	if (path_objects == NULL)
-		return got_error_from_errno();
+		return got_error_prefix_errno("got_repo_get_path_objects");
 
 	err = got_object_id_str(&hex, id);
 	if (err)
@@ -126,7 +126,7 @@ got_object_get_path(char **path, struct got_object_id *id,
 
 	if (asprintf(path, "%s/%.2x/%s", path_objects,
 	    id->sha1[0], hex + 2) == -1)
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("asprintf");
 
 done:
 	free(hex);
@@ -146,7 +146,7 @@ open_loose_object(int *fd, struct got_object_id *id,
 		return err;
 	*fd = open(path, O_RDONLY | O_NOFOLLOW);
 	if (*fd == -1) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno(path);
 		goto done;
 	}
 done:
@@ -166,7 +166,7 @@ get_packfile_path(char **path_packfile, struct got_packidx *packidx)
 
 	*path_packfile = malloc(size);
 	if (*path_packfile == NULL)
-		return got_error_from_errno();
+		return got_error_prefix_errno("malloc");
 
 	/* Copy up to and excluding ".idx". */
 	if (strlcpy(*path_packfile, packidx->path_packidx,
@@ -183,19 +183,16 @@ static void
 exec_privsep_child(int imsg_fds[2], const char *path, const char *repo_path)
 {
 	if (close(imsg_fds[0]) != 0) {
-		fprintf(stderr, "%s: %s\n", getprogname(),
-		    strerror(errno));
+		fprintf(stderr, "%s: %s\n", getprogname(), strerror(errno));
 		_exit(1);
 	}
 
 	if (dup2(imsg_fds[1], GOT_IMSG_FD_CHILD) == -1) {
-		fprintf(stderr, "%s: %s\n", getprogname(),
-		    strerror(errno));
+		fprintf(stderr, "%s: %s\n", getprogname(), strerror(errno));
 		_exit(1);
 	}
 	if (closefrom(GOT_IMSG_FD_CHILD + 1) == -1) {
-		fprintf(stderr, "%s: %s\n", getprogname(),
-		    strerror(errno));
+		fprintf(stderr, "%s: %s\n", getprogname(), strerror(errno));
 		_exit(1);
 	}
 
@@ -223,7 +220,7 @@ request_packed_object(struct got_object **obj, struct got_pack *pack, int idx,
 
 	(*obj)->path_packfile = strdup(pack->path_packfile);
 	if ((*obj)->path_packfile == NULL) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("strdup");
 		return err;
 	}
 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
@@ -241,23 +238,23 @@ start_pack_privsep_child(struct got_pack *pack, struct got_packidx *packidx)
 
 	ibuf = calloc(1, sizeof(*ibuf));
 	if (ibuf == NULL)
-		return got_error_from_errno();
+		return got_error_prefix_errno("calloc");
 
 	pack->privsep_child = calloc(1, sizeof(*pack->privsep_child));
 	if (pack->privsep_child == NULL) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("calloc");
 		free(ibuf);
 		return err;
 	}
 
 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, imsg_fds) == -1) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("socketpair");
 		goto done;
 	}
 
 	pid = fork();
 	if (pid == -1) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("fork");
 		goto done;
 	} else if (pid == 0) {
 		exec_privsep_child(imsg_fds, GOT_PATH_PROG_READ_PACK,
@@ -371,14 +368,14 @@ read_object_header_privsep(struct got_object **obj, struct got_repository *repo,
 
 	ibuf = calloc(1, sizeof(*ibuf));
 	if (ibuf == NULL)
-		return got_error_from_errno();
+		return got_error_prefix_errno("calloc");
 
 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, imsg_fds) == -1)
-		return got_error_from_errno();
+		return got_error_prefix_errno("socketpair");
 
 	pid = fork();
 	if (pid == -1)
-		return got_error_from_errno();
+		return got_error_prefix_errno("fork");
 	else if (pid == 0) {
 		exec_privsep_child(imsg_fds, GOT_PATH_PROG_READ_OBJECT,
 		    repo->path);
@@ -428,7 +425,7 @@ got_object_open(struct got_object **obj, struct got_repository *repo,
 		if (errno == ENOENT)
 			err = got_error_no_obj(id);
 		else
-			err = got_error_from_errno();
+			err = got_error_prefix_errno(path);
 		goto done;
 	} else {
 		err = read_object_header_privsep(obj, repo, fd);
@@ -471,7 +468,7 @@ got_object_resolve_id_str(struct got_object_id **id,
 	*id = got_object_id_dup(got_object_get_id(obj));
 	got_object_close(obj);
 	if (*id == NULL)
-		return got_error_from_errno();
+		return got_error_prefix_errno("got_object_id_dup");
 
 	return NULL;
 }
@@ -536,14 +533,14 @@ read_commit_privsep(struct got_commit_object **commit, int obj_fd,
 
 	ibuf = calloc(1, sizeof(*ibuf));
 	if (ibuf == NULL)
-		return got_error_from_errno();
+		return got_error_prefix_errno("calloc");
 
 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, imsg_fds) == -1)
-		return got_error_from_errno();
+		return got_error_prefix_errno("socketpair");
 
 	pid = fork();
 	if (pid == -1)
-		return got_error_from_errno();
+		return got_error_prefix_errno("fork");
 	else if (pid == 0) {
 		exec_privsep_child(imsg_fds, GOT_PATH_PROG_READ_COMMIT,
 		    repo->path);
@@ -641,11 +638,11 @@ got_object_qid_alloc(struct got_object_qid **qid, struct got_object_id *id)
 
 	*qid = calloc(1, sizeof(**qid));
 	if (*qid == NULL)
-		return got_error_from_errno();
+		return got_error_prefix_errno("calloc");
 
 	(*qid)->id = got_object_id_dup(id);
 	if ((*qid)->id == NULL) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("got_object_id_dup");
 		got_object_qid_free(*qid);
 		*qid = NULL;
 		return err;
@@ -714,14 +711,14 @@ read_tree_privsep(struct got_tree_object **tree, int obj_fd,
 
 	ibuf = calloc(1, sizeof(*ibuf));
 	if (ibuf == NULL)
-		return got_error_from_errno();
+		return got_error_prefix_errno("calloc");
 
 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, imsg_fds) == -1)
-		return got_error_from_errno();
+		return got_error_prefix_errno("socketpair");
 
 	pid = fork();
 	if (pid == -1)
-		return got_error_from_errno();
+		return got_error_prefix_errno("fork");
 	else if (pid == 0) {
 		exec_privsep_child(imsg_fds, GOT_PATH_PROG_READ_TREE,
 		    repo->path);
@@ -829,14 +826,14 @@ request_packed_blob(uint8_t **outbuf, size_t *size, size_t *hdrlen, int outfd,
 
 	basefd = got_opentempfd();
 	if (basefd == -1)
-		return got_error_from_errno();
+		return got_error_prefix_errno("got_opentempfd");
 	accumfd = got_opentempfd();
 	if (accumfd == -1)
-		return got_error_from_errno();
+		return got_error_prefix_errno("got_opentempfd");
 
 	outfd_child = dup(outfd);
 	if (outfd_child == -1)
-		return got_error_from_errno();
+		return got_error_prefix_errno("dup");
 
 	err = got_privsep_send_blob_req(pack->privsep_child->ibuf, -1, id, idx);
 	if (err)
@@ -868,7 +865,7 @@ request_packed_blob(uint8_t **outbuf, size_t *size, size_t *hdrlen, int outfd,
 		return err;
 
 	if (lseek(outfd, SEEK_SET, 0) == -1)
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("lseek");
 
 	return err;
 }
@@ -899,7 +896,7 @@ request_blob(uint8_t **outbuf, size_t *size, size_t *hdrlen, int outfd,
 
 	outfd_child = dup(outfd);
 	if (outfd_child == -1)
-		return got_error_from_errno();
+		return got_error_prefix_errno("dup");
 
 	err = got_privsep_send_blob_req(ibuf, infd, NULL, -1);
 	if (err)
@@ -914,7 +911,7 @@ request_blob(uint8_t **outbuf, size_t *size, size_t *hdrlen, int outfd,
 		return err;
 
 	if (lseek(outfd, SEEK_SET, 0) == -1)
-		return got_error_from_errno();
+		return got_error_prefix_errno("lseek");
 
 	return err;
 }
@@ -934,14 +931,14 @@ read_blob_privsep(uint8_t **outbuf, size_t *size, size_t *hdrlen,
 
 	ibuf = calloc(1, sizeof(*ibuf));
 	if (ibuf == NULL)
-		return got_error_from_errno();
+		return got_error_prefix_errno("calloc");
 
 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, imsg_fds) == -1)
-		return got_error_from_errno();
+		return got_error_prefix_errno("socketpair");
 
 	pid = fork();
 	if (pid == -1)
-		return got_error_from_errno();
+		return got_error_prefix_errno("fork");
 	else if (pid == 0) {
 		exec_privsep_child(imsg_fds, GOT_PATH_PROG_READ_BLOB,
 		    repo->path);
@@ -974,15 +971,15 @@ open_blob(struct got_blob_object **blob, struct got_repository *repo,
 
 	*blob = calloc(1, sizeof(**blob));
 	if (*blob == NULL)
-		return got_error_from_errno();
+		return got_error_prefix_errno("calloc");
 
 	outfd = got_opentempfd();
 	if (outfd == -1)
-		return got_error_from_errno();
+		return got_error_prefix_errno("got_opentempfd");
 
 	(*blob)->read_buf = malloc(blocksize);
 	if ((*blob)->read_buf == NULL) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("malloc");
 		goto done;
 	}
 
@@ -1026,14 +1023,14 @@ open_blob(struct got_blob_object **blob, struct got_repository *repo,
 		outfd = -1;
 		(*blob)->f = fmemopen(outbuf, size, "rb");
 		if ((*blob)->f == NULL) {
-			err = got_error_from_errno();
+			err = got_error_prefix_errno("fmemopen");
 			free(outbuf);
 			goto done;
 		}
 		(*blob)->data = outbuf;
 	} else {
 		if (fstat(outfd, &sb) == -1) {
-			err = got_error_from_errno();
+			err = got_error_prefix_errno("fstat");
 			goto done;
 		}
 
@@ -1044,7 +1041,7 @@ open_blob(struct got_blob_object **blob, struct got_repository *repo,
 
 		(*blob)->f = fdopen(outfd, "rb");
 		if ((*blob)->f == NULL) {
-			err = got_error_from_errno();
+			err = got_error_prefix_errno("fdopen");
 			close(outfd);
 			outfd = -1;
 			goto done;
@@ -1161,7 +1158,7 @@ got_object_blob_dump_to_file(size_t *total_len, int *nlines,
 	} while (len != 0);
 
 	if (fflush(outfile) != 0)
-		return got_error_from_errno();
+		return got_error_prefix_errno("fflush");
 	rewind(outfile);
 
 	return NULL;
@@ -1227,14 +1224,14 @@ read_tag_privsep(struct got_tag_object **tag, int obj_fd,
 
 	ibuf = calloc(1, sizeof(*ibuf));
 	if (ibuf == NULL)
-		return got_error_from_errno();
+		return got_error_prefix_errno("calloc");
 
 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, imsg_fds) == -1)
-		return got_error_from_errno();
+		return got_error_prefix_errno("socketpair");
 
 	pid = fork();
 	if (pid == -1)
-		return got_error_from_errno();
+		return got_error_prefix_errno("fork");
 	else if (pid == 0) {
 		exec_privsep_child(imsg_fds, GOT_PATH_PROG_READ_TAG,
 		    repo->path);
@@ -1385,7 +1382,7 @@ got_object_id_by_path(struct got_object_id **id, struct got_repository *repo,
 	if (path[1] == '\0') {
 		*id = got_object_id_dup(commit->tree_id);
 		if (*id == NULL)
-			err = got_error_from_errno();
+			err = got_error_prefix_errno("got_object_id_dup");
 		goto done;
 	}
 
@@ -1433,7 +1430,7 @@ got_object_id_by_path(struct got_object_id **id, struct got_repository *repo,
 	if (te) {
 		*id = got_object_id_dup(te->id);
 		if (*id == NULL)
-			return got_error_from_errno();
+			return got_error_prefix_errno("got_object_id_dup");
 	} else
 		err = got_error(GOT_ERR_NO_TREE_ENTRY);
 done:
@@ -1547,18 +1544,18 @@ got_object_tree_entry_dup(struct got_tree_entry **new_te,
 
 	*new_te = calloc(1, sizeof(**new_te));
 	if (*new_te == NULL)
-		return got_error_from_errno();
+		return got_error_prefix_errno("calloc");
 
 	(*new_te)->mode = te->mode;
 	(*new_te)->name = strdup(te->name);
 	if ((*new_te)->name == NULL) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("strdup");
 		goto done;
 	}
 
 	(*new_te)->id = got_object_id_dup(te->id);
 	if ((*new_te)->id == NULL) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("got_object_id_dup");
 		goto done;
 	}
 done:
diff --git a/lib/worktree.c b/lib/worktree.c
index 14285e5..4f7289e 100644
--- a/lib/worktree.c
+++ b/lib/worktree.c
@@ -65,7 +65,7 @@ create_meta_file(const char *path_got, const char *name, const char *content)
 	int fd = -1;
 
 	if (asprintf(&path, "%s/%s", path_got, name) == -1) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("asprintf");
 		path = NULL;
 		goto done;
 	}
@@ -73,7 +73,7 @@ create_meta_file(const char *path_got, const char *name, const char *content)
 	fd = open(path, O_RDWR | O_CREAT | O_EXCL | O_NOFOLLOW,
 	    GOT_DEFAULT_FILE_MODE);
 	if (fd == -1) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno(path);
 		goto done;
 	}
 
@@ -101,7 +101,7 @@ update_meta_file(const char *path_got, const char *name, const char *content)
 	char *path = NULL;
 
 	if (asprintf(&path, "%s/%s", path_got, name) == -1) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("asprintf");
 		path = NULL;
 		goto done;
 	}
@@ -113,13 +113,13 @@ update_meta_file(const char *path_got, const char *name, const char *content)
 	if (content) {
 		int len = fprintf(tmpfile, "%s\n", content);
 		if (len != strlen(content) + 1) {
-			err = got_error_from_errno();
+			err = got_error_prefix_errno(tmppath);
 			goto done;
 		}
 	}
 
 	if (rename(tmppath, path) != 0) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno(tmppath);
 		unlink(tmppath);
 		goto done;
 	}
@@ -127,7 +127,7 @@ update_meta_file(const char *path_got, const char *name, const char *content)
 done:
 	free(tmppath);
 	if (fclose(tmpfile) != 0 && err == NULL)
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("fclose");
 	return err;
 }
 
@@ -143,7 +143,7 @@ read_meta_file(char **content, const char *path_got, const char *name)
 	*content = NULL;
 
 	if (asprintf(&path, "%s/%s", path_got, name) == -1) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("asprintf");
 		path = NULL;
 		goto done;
 	}
@@ -153,28 +153,28 @@ read_meta_file(char **content, const char *path_got, const char *name)
 		if (errno == ENOENT)
 			err = got_error(GOT_ERR_WORKTREE_META);
 		else
-			err = got_error_from_errno();
+			err = got_error_prefix_errno(path);
 		goto done;
 	}
 	if (flock(fd, LOCK_SH | LOCK_NB) == -1) {
 		err = (errno == EWOULDBLOCK ? got_error(GOT_ERR_WORKTREE_BUSY)
-		    : got_error_from_errno());
+		    : got_error_prefix_errno("flock"));
 		goto done;
 	}
 
 	if (lstat(path, &sb) != 0) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno(path);
 		goto done;
 	}
 	*content = calloc(1, sb.st_size);
 	if (*content == NULL) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("calloc");
 		goto done;
 	}
 
 	n = read(fd, *content, sb.st_size);
 	if (n != sb.st_size) {
-		err = (n == -1 ? got_error_from_errno() :
+		err = (n == -1 ? got_error_prefix_errno(path) :
 		    got_error(GOT_ERR_WORKTREE_META));
 		goto done;
 	}
@@ -186,7 +186,7 @@ read_meta_file(char **content, const char *path_got, const char *name)
 
 done:
 	if (fd != -1 && close(fd) == -1 && err == NULL)
-		err = got_error_from_errno();
+		err = got_error_prefix_errno(path_got);
 	free(path);
 	if (err) {
 		free(*content);
@@ -232,17 +232,17 @@ got_worktree_init(const char *path, struct got_reference *head_ref,
 
 	/* Create top-level directory (may already exist). */
 	if (mkdir(path, GOT_DEFAULT_DIR_MODE) == -1 && errno != EEXIST) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno(path);
 		goto done;
 	}
 
 	/* Create .got directory (may already exist). */
 	if (asprintf(&path_got, "%s/%s", path, GOT_WORKTREE_GOT_DIR) == -1) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("asprintf");
 		goto done;
 	}
 	if (mkdir(path_got, GOT_DEFAULT_DIR_MODE) == -1 && errno != EEXIST) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno(path_got);
 		goto done;
 	}
 
@@ -303,7 +303,7 @@ got_worktree_init(const char *path, struct got_reference *head_ref,
 
 	/* Stamp work tree with format file. */
 	if (asprintf(&formatstr, "%d", GOT_WORKTREE_FORMAT_VERSION) == -1) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("asprintf");
 		goto done;
 	}
 	err = create_meta_file(path_got, GOT_WORKTREE_FORMAT, formatstr);
@@ -338,13 +338,13 @@ open_worktree(struct got_worktree **worktree, const char *path)
 	*worktree = NULL;
 
 	if (asprintf(&path_got, "%s/%s", path, GOT_WORKTREE_GOT_DIR) == -1) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("asprintf");
 		path_got = NULL;
 		goto done;
 	}
 
 	if (asprintf(&path_lock, "%s/%s", path_got, GOT_WORKTREE_LOCK) == -1) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("asprintf");
 		path_lock = NULL;
 		goto done;
 	}
@@ -352,7 +352,7 @@ open_worktree(struct got_worktree **worktree, const char *path)
 	fd = open(path_lock, O_RDWR | O_EXLOCK | O_NONBLOCK);
 	if (fd == -1) {
 		err = (errno == EWOULDBLOCK ? got_error(GOT_ERR_WORKTREE_BUSY)
-		    : got_error_from_errno());
+		    : got_error_prefix_errno(path_lock));
 		goto done;
 	}
 
@@ -372,14 +372,14 @@ open_worktree(struct got_worktree **worktree, const char *path)
 
 	*worktree = calloc(1, sizeof(**worktree));
 	if (*worktree == NULL) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("calloc");
 		goto done;
 	}
 	(*worktree)->lockfd = -1;
 
 	(*worktree)->root_path = strdup(path);
 	if ((*worktree)->root_path == NULL) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("strdup");
 		goto done;
 	}
 	err = read_meta_file(&(*worktree)->repo_path, path_got,
@@ -498,7 +498,7 @@ got_worktree_match_path_prefix(int *match, struct got_worktree *worktree,
 
 	if (!got_path_is_absolute(path_prefix)) {
 		if (asprintf(&absprefix, "/%s", path_prefix) == -1)
-			return got_error_from_errno();
+			return got_error_prefix_errno("asprintf");
 	}
 	*match = (strcmp(absprefix ? absprefix : path_prefix,
 	    worktree->path_prefix) == 0);
@@ -529,7 +529,7 @@ got_worktree_set_base_commit_id(struct got_worktree *worktree,
 
 	if (asprintf(&path_got, "%s/%s", worktree->root_path,
 	    GOT_WORKTREE_GOT_DIR) == -1) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("asprintf");
 		path_got = NULL;
 		goto done;
 	}
@@ -554,7 +554,7 @@ got_worktree_set_base_commit_id(struct got_worktree *worktree,
 	free(worktree->base_commit_id);
 	worktree->base_commit_id = got_object_id_dup(commit_id);
 	if (worktree->base_commit_id == NULL) {
-		err = got_error_from_errno();
+		err = got_error_prefix_errno("got_object_id_dup");
 		goto done;
 	}
 done:
@@ -570,7 +570,7 @@ lock_worktree(struct got_worktree *worktree, int operation)
 {
 	if (flock(worktree->lockfd, operation | LOCK_NB) == -1)
 		return (errno == EWOULDBLOCK ? got_error(GOT_ERR_WORKTREE_BUSY)
-		    : got_error_from_errno());
+		    : got_error_prefix_errno("flock"));
 	return NULL;
 }
 
@@ -581,14 +581,14 @@ add_dir_on_disk(struct got_worktree *worktree, const char *path)
 	char *abspath;
 
 	if (asprintf(&abspath, "%s/%s", worktree->root_path, path) == -1)
-		return got_error_from_errno();
+		return got_error_prefix_errno("asprintf");
 
 	err = got_path_mkdir(abspath);
 	if (err && err->code == GOT_ERR_ERRNO && errno == EEXIST) {
 		struct stat sb;
 		err = NULL;
 		if (lstat(abspath, &sb) == -1) {
-			err = got_error_from_errno();
+			err = got_error_prefix_errno("lstat");
 		} else if (!S_ISDIR(sb.st_mode)) {
 			/* TODO directory is obstructed; do something */
 			err = got_error(GOT_ERR_FILE_OBSTRUCTED);