From: Steinar H. Gunderson <steinar+git@gunderson.no>
Date: Fri, 19 Feb 2021 17:42:12 +0000 (+0100)
Subject: Support filesystems that do not support O_TMPFILE, even on Linux.
X-Git-Tag: 1.1.5~2
X-Git-Url: https://git.sesse.net/?p=plocate;a=commitdiff_plain;h=2ce489a666c51d516b1a1b40cd420397350c8f9f

Support filesystems that do not support O_TMPFILE, even on Linux.

Evidently, overlayfs does not support O_TMPFILE. Reported by Daniel Lewart.
---

diff --git a/database-builder.cpp b/database-builder.cpp
index da52cdb..75b05f6 100644
--- a/database-builder.cpp
+++ b/database-builder.cpp
@@ -485,24 +485,26 @@ DatabaseBuilder::DatabaseBuilder(const char *outfile, gid_t owner, int block_siz
 	if (path.empty()) {
 		path = ".";
 	}
+	int fd = -1;
 #ifdef O_TMPFILE
-	int fd = open(path.c_str(), O_WRONLY | O_TMPFILE, 0640);
-	if (fd == -1) {
+	fd = open(path.c_str(), O_WRONLY | O_TMPFILE, 0640);
+	if (fd == -1 && errno != EOPNOTSUPP) {
 		perror(path.c_str());
 		exit(1);
 	}
-#else
-	temp_filename = string(outfile) + ".XXXXXX";
-	int fd = mkstemp(&temp_filename[0]);
+#endif
 	if (fd == -1) {
-		perror(temp_filename.c_str());
-		exit(1);
-	}
-	if (fchmod(fd, 0640) == -1) {
-		perror("fchmod");
-		exit(1);
+		temp_filename = string(outfile) + ".XXXXXX";
+		fd = mkstemp(&temp_filename[0]);
+		if (fd == -1) {
+			perror(temp_filename.c_str());
+			exit(1);
+		}
+		if (fchmod(fd, 0640) == -1) {
+			perror("fchmod");
+			exit(1);
+		}
 	}
-#endif
 
 	if (owner != (gid_t)-1) {
 		if (fchown(fd, (uid_t)-1, owner) == -1) {
@@ -679,22 +681,24 @@ void DatabaseBuilder::finish_corpus()
 	fseek(outfp, 0, SEEK_SET);
 	fwrite(&hdr, sizeof(hdr), 1, outfp);
 
+	if (!temp_filename.empty()) {
+		if (rename(temp_filename.c_str(), outfile.c_str()) == -1) {
+			perror("rename");
+			exit(1);
+		}
+	} else {
 #ifdef O_TMPFILE
-	// Give the file a proper name, making it visible in the file system.
-	// TODO: It would be nice to be able to do this atomically, like with rename.
-	unlink(outfile.c_str());
-	char procpath[256];
-	snprintf(procpath, sizeof(procpath), "/proc/self/fd/%d", fileno(outfp));
-	if (linkat(AT_FDCWD, procpath, AT_FDCWD, outfile.c_str(), AT_SYMLINK_FOLLOW) == -1) {
-		perror("linkat");
-		exit(1);
-	}
-#else
-	if (rename(temp_filename.c_str(), outfile.c_str()) == -1) {
-		perror("rename");
-		exit(1);
-	}
+		// Give the file a proper name, making it visible in the file system.
+		// TODO: It would be nice to be able to do this atomically, like with rename.
+		unlink(outfile.c_str());
+		char procpath[256];
+		snprintf(procpath, sizeof(procpath), "/proc/self/fd/%d", fileno(outfp));
+		if (linkat(AT_FDCWD, procpath, AT_FDCWD, outfile.c_str(), AT_SYMLINK_FOLLOW) == -1) {
+			perror("linkat");
+			exit(1);
+		}
 #endif
+	}
 
 	fclose(outfp);
 
diff --git a/database-builder.h b/database-builder.h
index 0c25476..89fbc7c 100644
--- a/database-builder.h
+++ b/database-builder.h
@@ -81,9 +81,7 @@ public:
 private:
 	FILE *outfp;
 	std::string outfile;
-#ifndef O_TMPFILE
 	std::string temp_filename;
-#endif
 	Header hdr;
 	const int block_size;
 	std::chrono::steady_clock::time_point corpus_start;