Added add_backing

src/utils.c

@@ -10,7 +10,7 @@
 #include <errno.h>
 #include <dirent.h>
 #include <fcntl.h>
-#include <openssl/md5.h>
+#include <openssl/evp.h>
 
 char ERROR_BUFFER[ERROR_BUFFER_SIZE];
 
@@ -412,6 +412,62 @@ result_t write_file(const char* path, const char* str) {
 	return result;
 }
 
+result_t copy_file(const char* src, const char* dst) {
+	// Open the source file
+	errno = 0;
+	int src_fd = open(src, O_RDONLY);
+	if (src_fd < 0)
+		return failure("Failed to open the source file '%s' (%s).", src, strerror(errno));
+
+	// Open the destination file
+	errno = 0;
+	int dst_fd = open(dst, O_WRONLY | O_CREAT | O_TRUNC, 0644);
+	if (dst_fd < 0) {
+		close(src_fd);
+		return failure("Failed to open the destination file '%s' (%s).", dst, strerror(errno));
+	}
+
+	// Copy the source file to the destination file
+	char buffer[4096];
+	ssize_t count;
+
+	while (1) {
+		// Read from the source file
+		errno = 0;
+		count = read(src_fd, buffer, sizeof(buffer));
+		if (count < 0) {
+			close(src_fd);
+			close(dst_fd);
+			return failure("Failed to read from the source file '%s' (%s).", src, strerror(errno));
+		}
+
+		// If the end of the file is reached, stop copying
+		if (count == 0)
+			break;
+
+		// Write to the destination file
+		while (count > 0) {
+			errno = 0;
+			ssize_t written = write(dst_fd, buffer, count);
+			if (written < 0) {
+				close(src_fd);
+				close(dst_fd);
+				return failure("Failed to write to the destination file '%s' (%s).", dst, strerror(errno));
+			}
+
+			count -= written;
+		}
+	}
+
+	// Close the source file
+	close(src_fd);
+
+	// Close the destination file
+	close(dst_fd);
+
+	return success();
+}
+
 result_t list_files(char*** _files, const char* path, bool (*filter)(const char*)) {
 	// Initialize the output parameters
 	*_files = NULL;
@@ -493,3 +549,85 @@ result_t list_files(char*** _files, const char* path, bool (*filter)(const char*
 	*_files = files;
 	return success();
 }
+
+result_t md5sum(char** _md5, const char* path) {
+	// Initialize the output parameters
+	*_md5 = NULL;
+
+	// Open the file
+	errno = 0;
+	int fd = open(path, O_RDONLY);
+	if (fd < 0)
+		return failure("Failed to open the file '%s' (%s).", path, strerror(errno));
+
+	// Initialize the MD5 context
+	EVP_MD_CTX* mdctx = EVP_MD_CTX_new();
+	if (mdctx == NULL) {
+		close(fd);
+		return failure("Failed to initialize the MD5 context.");
+	}
+
+	if (EVP_DigestInit_ex(mdctx, EVP_md5(), NULL) != 1) {
+		EVP_MD_CTX_free(mdctx);
+		close(fd);
+		return failure("Failed to initialize the MD5 context.");
+	}
+
+	// Read the file and update the MD5 context
+	char buffer[4096];
+	ssize_t count;
+
+	while (1) {
+		// Read from the file
+		errno = 0;
+		count = read(fd, buffer, sizeof(buffer));
+		if (count < 0) {
+			EVP_MD_CTX_free(mdctx);
+			close(fd);
+			return failure("Failed to read from the file '%s' (%s).", path, strerror(errno));
+		}
+
+		// If the end of the file is reached, stop updating the MD5 context
+		if (count == 0)
+			break;
+
+		// Update the MD5 context
+		if (EVP_DigestUpdate(mdctx, buffer, count) != 1) {
+			EVP_MD_CTX_free(mdctx);
+			close(fd);
+			return failure("Failed to update the MD5 context.");
+		}
+	}
+
+	// Finalize the MD5 context
+	unsigned char md_value[EVP_MAX_MD_SIZE];
+	unsigned int md_len;
+
+	if (EVP_DigestFinal_ex(mdctx, md_value, &md_len) != 1) {
+		EVP_MD_CTX_free(mdctx);
+		close(fd);
+		return failure("Failed to finalize the MD5 context.");
+	}
+
+	EVP_MD_CTX_free(mdctx);
+
+	// Close the file
+	close(fd);
+
+	// Format the MD5 checksum
+	errno = 0;
+	char* md5 = malloc(2 * md_len + 1); // +1 for the null terminator
+	if (md5 == NULL)
+		return failure("Failed to allocate memory for the MD5 checksum (%s).", strerror(errno));
+
+	for (unsigned int i = 0; i < md_len; i++)
+		if (snprintf(md5 + 2 * i, 3, "%02x", md_value[i]) != 2) {
+			free(md5);
+			return failure("Failed to format the MD5 checksum.");
+		}
+	md5[2 * md_len] = '\0';
+
+	// Return the MD5 checksum
+	*_md5 = md5;
+	return success();
+}