libvieter/src/package/package.c

#include "package.h"
#include "sha256.h"

#define SMALL_BUFF_SIZE 128

#define ADD_STRING(section, field) if (pkg_info->field != 0) { \
	snprintf(aux, SMALL_BUFF_SIZE, section, pkg_info->field); \
	if (buff_size < strlen(description) + SMALL_BUFF_SIZE + 1) { \
		description = realloc(description, buff_size * 2); \
		buff_size *= 2; \
	} \
	strcat(description, aux); \
}
#define ADD_ARRAY(section, field) i = 0; if (pkg_info->field != NULL) { \
	snprintf(aux, SMALL_BUFF_SIZE, section, pkg_info->field->array[i]); i++; \
	if (buff_size < strlen(description) + SMALL_BUFF_SIZE + 1) { \
		description = realloc(description, buff_size * 2); \
		buff_size *= 2; \
	} \
	strcat(description, aux); \
	while (pkg_info->field->array[i] != NULL) { \
	snprintf(aux, SMALL_BUFF_SIZE, "\n%s", pkg_info->field->array[i]); i++; \
		if (buff_size < strlen(description) + SMALL_BUFF_SIZE + 1) { \
			description = realloc(description, buff_size * 2); \
			buff_size *= 2; \
		} \
		strcat(description, aux); \
	} \
}

static char *ignored_names[5] = {
	".BUILDINFO",
	".INSTALL",
	".MTREE",
	".PKGINFO",
	".CHANGELOG"
};
static size_t ignored_words_len = sizeof(ignored_names) / sizeof(char *);

Pkg *package_init() {
	return calloc(sizeof(PkgInfo), 1);
}

Pkg *package_read_archive(const char *pkg_path) {
	struct archive *a = archive_read_new();
	struct archive_entry *entry = archive_entry_new();

	// These three are the most commonly used compression methods
	archive_read_support_filter_zstd(a);
	archive_read_support_filter_gzip(a);
	archive_read_support_filter_xz(a);

	// Contents should always be a tarball
	archive_read_support_format_tar(a);

	// TODO where does this 10240 come from?
	int r = archive_read_open_filename(a, pkg_path, 10240);

	// Exit early if we weren't able to successfully open the archive for reading
	if (r != ARCHIVE_OK) {
		return NULL;
	}

	int compression_code = archive_filter_code(a, 0);
	const char *path_name;

	PkgInfo *pkg_info;
	DynArray *files = dynarray_init(16);
	dynarray_add(files, "%FILES%");

	while (archive_read_next_header(a, &entry) == ARCHIVE_OK) {
		path_name = archive_entry_pathname(entry);

		bool ignore = false;

		for (size_t i = 0; i < ignored_words_len; i++) {
			if (strcmp(path_name, ignored_names[i]) == 0) {
				ignore = true;
				break;
			}
		}

		if (!ignore) {
			dynarray_add(files, path_name);
		}

		if (strcmp(path_name, ".PKGINFO") == 0) {
			// Read data of file into memory buffer
			int size = archive_entry_size(entry);
			char *buf = malloc(size);
			archive_read_data(a, buf, size);

			// Parse package info string into a struct
			pkg_info = package_info_init();
			package_info_parse(pkg_info, buf);

			free(buf);
		} else {
			archive_read_data_skip(a);
		}
	}

	// Get size of file
	struct stat stats;

	if (stat(pkg_path, &stats) != 0) {
		return NULL;
	}

	pkg_info->csize = stats.st_size;

	archive_read_free(a);

	// Create final return value
	Pkg *pkg = package_init();
	pkg->path = strdup(pkg_path);
	pkg->info = pkg_info;
	pkg->files = files;
	pkg->compression = compression_code;

	return pkg;
}

void sha256sum(Pkg *pkg, char *res) {
	FILE *f = fopen(pkg->path, "r");
	fseek(f, 0, SEEK_END);
	size_t size = ftell(f);
	rewind(f);
	unsigned char *in = malloc(size);
	fread(in, 1, size, f);
	fclose(f);

	unsigned char hash[32];
	SHA256_CTX *ctx = malloc(sizeof(SHA256_CTX));

	sha256_init(ctx);
	sha256_update(ctx, in, size);
	sha256_final(ctx, hash);

	free(in);
	free(ctx);

	// We need to convert the bytes in the hash to get a string representation of its hex values
	// i.e. turn 1001 1111 into the string "9f"
	// Each byte of the hash is going to turn into two bytes in the final string
	// so we are going to convert each half byte into a char
	unsigned int half_byte = 0;
	int j = 0;

	// We advance in the string 2 bytes for every one byte of the hash
	for (int i = 0; i < 32; i++) {
		// We transform the first half byte into the second character to keep
		// each byte from becoming reversed in the final string
		half_byte = hash[i] & 0b1111;
		if (half_byte < 10) {
			res[j+1] = half_byte + 48;
		} else {
			res[j+1] = half_byte + 87;
		}
		hash[i] = hash[i] >> 4;
		half_byte = hash[i] & 0b1111;
		if (half_byte < 10) {
			res[j] = half_byte + 48;
		} else {
			res[j] = half_byte + 87;
		}

		j += 2;
	}
	res[j] = '\0';
}

char *package_to_description(Pkg *pkg) {
	PkgInfo *pkg_info = pkg->info;

	size_t buff_size = 1024;
	char aux[SMALL_BUFF_SIZE];
	char *description = malloc(sizeof(char) * buff_size);
	int i;

	// special case for FILENAME
	// assuming .pkg.tar.zst; other formats are valid, this should account for that
	snprintf(aux, SMALL_BUFF_SIZE, "%%FILENAME%%\n%s-%s-%s.pkg.tar.zst", pkg_info->name, pkg_info->version,
			pkg_info->arch);
	strcpy(description, aux);

	ADD_STRING("\n\n%%NAME%%\n%s", name);
	ADD_STRING("\n\n%%BASE%%\n%s", base);
	ADD_STRING("\n\n%%VERSION%%\n%s", version);
	ADD_STRING("\n\n%%DESC%%\n%s", description);
	ADD_ARRAY("\n\n%%GROUPS%%\n%s", groups);
	ADD_STRING("\n\n%%CSIZE%%\n%ld", csize);
	ADD_STRING("\n\n%%ISIZE%%\n%ld", size);

	char checksum[65];
	sha256sum(pkg, checksum);

	snprintf(aux, SMALL_BUFF_SIZE, "\n\n%%SHA256SUM%%\n%s", checksum);
	if (buff_size < strlen(description) + SMALL_BUFF_SIZE + 1) {
		description = realloc(description, buff_size * 2);
		buff_size *= 2;
	}
	strcat(description, aux);

	ADD_STRING("\n\n%%URL%%\n%s", url);
	ADD_ARRAY("\n\n%%LICENSE%%\n%s", licenses);
	ADD_STRING("\n\n%%ARCH%%\n%s", arch);
	ADD_STRING("\n\n%%BUILDDATE%%\n%ld", build_date);
	ADD_STRING("\n\n%%PACKAGER%%\n%s", packager);
	ADD_ARRAY("\n\n%%REPLACES%%\n%s", replaces);
	ADD_ARRAY("\n\n%%CONFLICTS%%\n%s", conflicts);
	ADD_ARRAY("\n\n%%PROVIDES%%\n%s", provides);
	ADD_ARRAY("\n\n%%DEPENDS%%\n%s", depends);
	ADD_ARRAY("\n\n%%OPTDEPENDS%%\n%s", optdepends);
	ADD_ARRAY("\n\n%%MAKEDEPENDS%%\n%s", makedepends);
	ADD_ARRAY("\n\n%%CHECKDEPENDS%%\n%s", checkdepends);

	snprintf(aux, SMALL_BUFF_SIZE, "\n\n");
	strcat(description, aux);

	return description;
}