Extend the functionality of bin/fstrim

Improvements:
* Introduce new command-line parameters for the offset and length
  of the trimmed region
* Introduce a new command-line parameter that must be specified
  in order to trim a block/character device instead of a file system
* By default, warn users that trim can potentially destroy data
* Display the number of bytes trimmed even if the ioctl returns
  an error

Change-Id: I9eec535abe74f7ef09c927292a120016f4156684
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4154
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

src/bin/fstrim.cpp

@@ -1,6 +1,7 @@
 /*
- * Copyright 2013, Axel Dörfler, axeld@pinc-software.de.
+ * Copyright 2021 David Sebek, dasebek@gmail.com
- * Distributed under the terms of the MIT license.
+ * Copyright 2013 Axel Dörfler, axeld@pinc-software.de
+ * All rights reserved. Distributed under the terms of the MIT License.
  */
 
 
@@ -12,6 +13,9 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include <sys/types.h>
+#include <sys/stat.h>
+
 #include <Drivers.h>
 
 #include <AutoDeleter.h>
@@ -19,41 +23,183 @@
 
 static struct option const kLongOptions[] = {
 	{"help", no_argument, 0, 'h'},
+	{"offset", required_argument, 0, 'o'},
+	{"length", required_argument, 0, 'l'},
+	{"discard-device", no_argument, 0, 'd'},
+	{"force", no_argument, 0, 'f'},
+	{"verbose", no_argument, 0, 'v'},
 	{NULL}
 };
 
 
-extern const char *__progname;
+extern const char* __progname;
-static const char *kProgramName = __progname;
+static const char* kProgramName = __progname;
 
 
 void
-usage(int returnValue)
+PrintUsage(void)
 {
-	fprintf(stderr, "Usage: %s <path-to-mounted-file-system>\n", kProgramName);
+	fprintf(stderr, "Usage: %s [options] <path-to-mounted-file-system>\n",
-	exit(returnValue);
+		kProgramName);
+	fprintf(stderr, "\n");
+	fprintf(stderr, "%s reports unused blocks to a storage device.\n",
+		kProgramName);
+	fprintf(stderr, "\n");
+	fprintf(stderr, "List of options:\n");
+	fprintf(stderr, " -o, --offset <num>  Start of the trimmed region in bytes (default: 0)\n");
+	fprintf(stderr, " -l, --length <num>  Length of the trimmed region in bytes. Trimming will stop\n");
+	fprintf(stderr, "                     when a file system/device boundary is reached.\n");
+	fprintf(stderr, "                     (default: trim until the end)\n");
+	fprintf(stderr, " --discard-device    Trim a block or character device directly instead of\n");
+	fprintf(stderr, "                     a file system. DANGEROUS: erases data on the device!\n");
+	fprintf(stderr, "\n");
+	fprintf(stderr, " -f, --force         Do not ask user for confirmation of dangerous operations\n");
+	fprintf(stderr, " -v, --verbose       Enable verbose messages\n");
+	fprintf(stderr, " -h, --help          Display this help\n");
+}
+
+
+bool
+IsDirectory(const int fd)
+{
+	struct stat fdStat;
+	if (fstat(fd, &fdStat) == -1) {
+		fprintf(stderr, "%s: fstat failed: %s\n", kProgramName,
+			strerror(errno));
+		return false;
+	}
+	return S_ISDIR(fdStat.st_mode);
+}
+
+
+bool
+IsBlockDevice(const int fd)
+{
+	struct stat fdStat;
+	if (fstat(fd, &fdStat) == -1) {
+		fprintf(stderr, "%s: fstat failed: %s\n", kProgramName,
+			strerror(errno));
+		return false;
+	}
+	return S_ISBLK(fdStat.st_mode);
+}
+
+
+bool
+IsCharacterDevice(const int fd)
+{
+	struct stat fdStat;
+	if (fstat(fd, &fdStat) == -1) {
+		fprintf(stderr, "%s: fstat failed: %s\n", kProgramName,
+			strerror(errno));
+		return false;
+	}
+	return S_ISCHR(fdStat.st_mode);
+}
+
+
+int
+YesNoPrompt(const char* message)
+{
+	char* buffer;
+	size_t bufferSize;
+	ssize_t inputLength;
+
+	if (message != NULL)
+		printf("%s\n", message);
+
+	while (true) {
+		printf("Answer [yes/NO]: ");
+
+		buffer = NULL;
+		bufferSize = 0;
+		inputLength = getline(&buffer, &bufferSize, stdin);
+
+		MemoryDeleter deleter(buffer);
+
+		if (inputLength == -1) {
+			fprintf(stderr, "%s: getline failed: %s\n", kProgramName,
+				strerror(errno));
+			return -1;
+		}
+
+		if (strncasecmp(buffer, "yes\n", bufferSize) == 0)
+			return 1;
+
+		if (strncasecmp(buffer, "no\n", bufferSize) == 0
+			|| strncmp(buffer, "\n", bufferSize) == 0)
+			return 0;
+	}
+}
+
+
+bool
+ParseUint64(const char* string, uint64* value)
+{
+	uint64 parsedValue;
+	char dummy;
+
+	if (string == NULL || value == NULL)
+		return false;
+
+	if (sscanf(string, "%" B_SCNu64 "%c", &parsedValue, &dummy) == 1) {
+		*value = parsedValue;
+		return true;
+	}
+	return false;
 }
 
 
 int
 main(int argc, char** argv)
 {
+	bool discardDevice = false;
+	bool force = false;
+	bool verbose = false;
+	uint64 offset = 0;
+	uint64 length = UINT64_MAX;
+
 	int c;
-	while ((c = getopt_long(argc, argv, "h", kLongOptions, NULL)) != -1) {
+	while ((c = getopt_long(argc, argv, "ho:l:fv", kLongOptions, NULL)) != -1) {
 		switch (c) {
 			case 0:
 				break;
+			case 'o':
+				if (!ParseUint64(optarg, &offset)) {
+					fprintf(stderr, "%s: Invalid offset value\n", kProgramName);
+					return EXIT_FAILURE;
+				}
+				break;
+			case 'l':
+				if (!ParseUint64(optarg, &length)) {
+					fprintf(stderr, "%s: Invalid length value\n", kProgramName);
+					return EXIT_FAILURE;
+				}
+				break;
+			case 'd':
+				discardDevice = true;
+				break;
+			case 'f':
+				force = true;
+				break;
+			case 'v':
+				verbose = true;
+				break;
 			case 'h':
-				usage(0);
+				PrintUsage();
+				return EXIT_SUCCESS;
 				break;
 			default:
-				usage(1);
+				PrintUsage();
+				return EXIT_FAILURE;
 				break;
 		}
 	}
 
-	if (argc - optind < 1)
+	if (argc - optind < 1) {
-		usage(1);
+		PrintUsage();
+		return EXIT_FAILURE;
+	}
 	const char* path = argv[optind++];
 
 	int fd = open(path, O_RDONLY);
@@ -65,18 +211,60 @@ main(int argc, char** argv)
 
 	FileDescriptorCloser closer(fd);
 
+	if (IsDirectory(fd)) {
+		if (discardDevice) {
+			fprintf(stderr, "%s: Block or character device requested but %s"
+				" is a directory\n", kProgramName, path);
+			return EXIT_FAILURE;
+		}
+
+		if (!force && YesNoPrompt("Trim support in Haiku is experimental and"
+				" may result in data loss.\nContinue anyway?") != 1) {
+			fprintf(stderr, "%s: Operation canceled by the user\n",
+				kProgramName);
+			return EXIT_SUCCESS;
+		}
+	} else if (IsBlockDevice(fd) || IsCharacterDevice(fd)) {
+		if (!discardDevice) {
+			fprintf(stderr, "%s: --discard-device must be specified to trim"
+				" a block or character device\n", kProgramName);
+			return EXIT_FAILURE;
+		}
+
+		if (!force && YesNoPrompt("Do you really want to PERMANENTLY ERASE"
+				" data from the specified device?") != 1) {
+			fprintf(stderr, "%s: Operation canceled by the user\n",
+				kProgramName);
+			return EXIT_SUCCESS;
+		}
+	} else {
+		fprintf(stderr, "%s: %s is neither a directory nor a block or"
+			" character device\n", kProgramName, path);
+		return EXIT_FAILURE;
+	}
+
 	fs_trim_data trimData;
 	trimData.range_count = 1;
-	trimData.ranges[0].offset = 0;
+	trimData.ranges[0].offset = offset;
-	trimData.ranges[0].size = UINT64_MAX;
+	trimData.ranges[0].size = length;
 	trimData.trimmed_size = 0;
 
+	if (verbose) {
+		printf("Range to trim (bytes): offset = %" B_PRIu64
+			", length = %" B_PRIu64 "\n", offset, length);
+	}
+
+	int retval = EXIT_SUCCESS;
+
 	if (ioctl(fd, B_TRIM_DEVICE, &trimData, sizeof(fs_trim_data)) != 0) {
 		fprintf(stderr, "%s: Trimming failed: %s\n", kProgramName,
 			strerror(errno));
-		return EXIT_FAILURE;
+		retval = EXIT_FAILURE;
 	}
 
-	printf("Trimmed %" B_PRIu64 " bytes from device.\n", trimData.trimmed_size);
+	printf("Trimmed %" B_PRIu64 " bytes from device%s.\n",
-	return EXIT_SUCCESS;
+		trimData.trimmed_size,
+		retval == EXIT_SUCCESS ? "" : " (number may be inaccurate)");
+
+	return retval;
 }