userspace: Implement mv utility

userspace/programs/CMakeLists.txt

@@ -30,6 +30,7 @@ set(USERSPACE_PROGRAMS
 	ls
 	meminfo
 	mkdir
+	mv
 	nologin
 	nslookup
 	poweroff

userspace/programs/mv/CMakeLists.txt

@@ -0,0 +1,8 @@
+set(SOURCES
+	main.cpp
+)
+
+add_executable(mv ${SOURCES})
+banan_link_library(mv libc)
+
+install(TARGETS mv OPTIONAL)

userspace/programs/mv/main.cpp

@@ -0,0 +1,251 @@
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <libgen.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+static int copy_file(const char* src, const char* dst)
+{
+	struct stat src_st;
+	if (stat(src, &src_st) == -1)
+		return errno;
+
+	struct stat dst_st;
+	if (stat(dst, &dst_st) == 0)
+	{
+		if (S_ISDIR(dst_st.st_mode))
+			return EINVAL;
+		if (unlinkat(AT_FDCWD, dst, 0) == -1)
+			return errno;
+	}
+
+	if (S_ISREG(src_st.st_mode))
+	{
+		const int src_fd = open(src, O_RDONLY);
+		const int dst_fd = open(dst, O_RDWR | O_CREAT | O_EXCL, src_st.st_mode);
+
+		if (src_fd == -1 || dst_fd == -1)
+		{
+			if (src_fd != -1)
+				close(src_fd);
+			if (dst_fd != -1)
+				close(dst_fd);
+			return errno;
+		}
+
+		int result = 0;
+
+		char buffer[512];
+		for (;;)
+		{
+			const ssize_t nread = read(src_fd, buffer, 512);
+			if (nread <= 0)
+			{
+				if (nread == -1)
+					result = errno;
+				break;
+			}
+
+			ssize_t total_written = 0;
+			while (total_written < nread)
+			{
+				const ssize_t nwrite = write(dst_fd, buffer + total_written, nread - total_written);
+				if (nwrite < 0)
+				{
+					result = errno;
+					break;
+				}
+				total_written += nwrite;
+			}
+		}
+
+		if (result == 0 && unlink(src) == -1)
+			result = errno;
+
+		close(src_fd);
+		close(dst_fd);
+		return result;
+	}
+
+	if (S_ISLNK(src_st.st_mode))
+	{
+		char* buffer = static_cast<char*>(malloc(512));
+		if (buffer == nullptr)
+			return errno;
+		ssize_t buffer_size = 512;
+
+		ssize_t link_len;
+		while ((link_len = readlink(src, buffer, buffer_size)) == buffer_size)
+		{
+			buffer_size *= 2;
+			void* new_buffer = realloc(buffer, buffer_size);
+			if (new_buffer == nullptr)
+			{
+				free(buffer);
+				return errno;
+			}
+			buffer = static_cast<char*>(new_buffer);
+		}
+
+		int result = 0;
+		if (link_len == -1)
+			result = errno;
+		if (result == 0 && symlink(buffer, dst) == -1)
+			result = errno;
+		if (result == 0 && unlink(src) == -1)
+			result = errno;
+		free(buffer);
+		return result;
+	}
+
+	fprintf(stddbg, "move file with mode %07o to another filesystem\n", src_st.st_mode);
+	return ENOTSUP;
+}
+
+static int copy_directory(const char* src, const char* dst)
+{
+	struct stat src_st;
+	if (stat(src, &src_st) == -1)
+		return errno;
+
+	struct stat dst_st;
+	if (stat(dst, &dst_st) == 0)
+	{
+		if (!S_ISDIR(dst_st.st_mode))
+			return ENOTDIR;
+		if (rmdir(dst) == -1)
+			return errno;
+	}
+
+	if (mkdir(dst, src_st.st_mode) == -1)
+		return errno;
+
+	DIR* dirp = opendir(src);
+	if (dirp == nullptr)
+		return errno;
+
+	int result = 0;
+
+	dirent* dent;
+	while ((dent = readdir(dirp)))
+	{
+		if (strcmp(dent->d_name, ".") == 0 || strcmp(dent->d_name, "..") == 0)
+			continue;
+
+		bool name_too_long = false;
+
+		char src_buffer[PATH_MAX];
+		if (snprintf(src_buffer, PATH_MAX, "%s/%s", src, dent->d_name) > PATH_MAX)
+			name_too_long = true;
+
+		char dst_buffer[PATH_MAX];
+		if (snprintf(dst_buffer, PATH_MAX, "%s/%s", dst, dent->d_name) > PATH_MAX)
+			name_too_long = true;
+
+		if (name_too_long)
+			result = ENAMETOOLONG;
+		else
+		{
+			auto* copy_func = (dent->d_type == DT_DIR) ? copy_directory : copy_file;
+			if (int ret = copy_func(src_buffer, dst_buffer))
+				result = ret;
+		}
+	}
+
+	if (result == 0 && rmdir(src) == -1)
+		result = errno;
+
+	closedir(dirp);
+
+	return result;
+}
+
+static int do_move(const char* src, const char* dest)
+{
+	char buffer[PATH_MAX];
+
+	struct stat st;
+	if (stat(dest, &st) == 0 && S_ISDIR(st.st_mode))
+	{
+		if (snprintf(buffer, PATH_MAX, "%s/%s", dest, basename(const_cast<char*>(src))) > PATH_MAX)
+			return ENAMETOOLONG;
+		dest = buffer;
+	}
+
+	if (rename(src, dest) == 0)
+		return 0;
+
+	if (errno != EXDEV)
+		return errno;
+
+	if (stat(src, &st) == -1)
+		return errno;
+
+	auto* copy_func = S_ISDIR(st.st_mode) ? copy_directory : copy_file;
+	return copy_func(src, dest);
+}
+
+int main(int argc, char** argv)
+{
+	for (;;)
+	{
+		static option long_options[] {
+			{ "help", no_argument, nullptr, 'h' },
+		};
+
+		int ch = getopt_long(argc, argv, "h", long_options, nullptr);
+		if (ch == -1)
+			break;
+
+		switch (ch)
+		{
+			case 'h':
+				printf("usage: %s [OPTIONS]... SOURCE... DEST\n", argv[0]);
+				printf("Moves files SOURCE... to DEST\n");
+				printf("OPTIONS:\n");
+				printf("    -h, --help   Show this message and exit\n");
+				return 0;
+			case '?':
+				fprintf(stderr, "invalid option %c\n", optopt);
+				fprintf(stderr, "see '%s --help' for usage\n", argv[0]);
+				return 1;
+		}
+	}
+
+	const int src_count = argc - optind - 1;
+	if (src_count < 1)
+	{
+		fprintf(stderr, "missing destination operand\n");
+		return 1;
+	}
+
+	const char* dest = argv[argc - 1];
+
+	if (src_count >= 2)
+	{
+		struct stat st;
+		if (stat(dest, &st) == -1 || !S_ISDIR(st.st_mode))
+		{
+			fprintf(stderr, "destination is not a directory\n");
+			return 1;
+		}
+	}
+
+	int result = 0;
+	for (int i = optind; i < argc - 1; i++)
+	{
+		if (int ret = do_move(argv[i], dest); ret != 0)
+		{
+			fprintf(stderr, "%s: %s\n", argv[0], strerror(ret));
+			result = 1;
+		}
+	}
+
+	return result;
+}