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// Test for MinGW.
#if defined(__MINGW32__) || defined(__MINGW64__)
# define MINGW
#endif
// Decide if the writev(2) system call needs to be emulated as a series of
// write(2) calls. At least MinGW does not support writev(2).
#ifdef MINGW
# define EMULATE_WRITEV
#endif
// Include the necessary system header when using the system's writev(2).
#ifndef EMULATE_WRITEV
# define _XOPEN_SOURCE // Unlock IOV_MAX
# include <sys/uio.h>
#endif
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <getopt.h>
#include <errno.h>
#include <limits.h>
#include "../include/libbase64.h"
// Size of the buffer for the "raw" (not base64-encoded) data in bytes.
#define BUFFER_RAW_SIZE (1024 * 1024)
// Size of the buffer for the base64-encoded data in bytes. The base64-encoded
// data is 4/3 the size of the input, with some margin to be sure.
#define BUFFER_ENC_SIZE (BUFFER_RAW_SIZE * 4 / 3 + 16)
// Global config structure.
struct config {
// Name by which the program was called on the command line.
const char *name;
// Name of the input file for logging purposes.
const char *file;
// Input file handle.
FILE *fp;
// Wrap width in characters, for encoding only.
size_t wrap;
// Whether to run in decode mode.
bool decode;
// Whether to just print the help text and exit.
bool print_help;
};
// Input/output buffer structure.
struct buffer {
// Runtime-allocated buffer for raw (unencoded) data.
char *raw;
// Runtime-allocated buffer for base64-encoded data.
char *enc;
};
// Optionally emulate writev(2) as a series of write calls.
#ifdef EMULATE_WRITEV
// Quick and dirty definition of IOV_MAX as it is probably not defined.
#ifndef IOV_MAX
# define IOV_MAX 1024
#endif
// Quick and dirty definition of this system struct, for local use only.
struct iovec {
// Opaque data pointer.
void *iov_base;
// Length of the data in bytes.
size_t iov_len;
};
static ssize_t
writev (const int fd, const struct iovec *iov, int iovcnt)
{
ssize_t r, nwrite = 0;
// Reset the error marker.
errno = 0;
while (iovcnt-- > 0) {
// Write the vector; propagate errors back to the caller. Note
// that this loses information about how much vectors have been
// successfully written, but that also seems to be the case
// with the real function. The API is somewhat flawed.
if ((r = write(fd, iov->iov_base, iov->iov_len)) < 0) {
return r;
}
// Update the total write count.
nwrite += r;
// Return early after a partial write; the caller should retry.
if ((size_t) r != iov->iov_len) {
break;
}
// Move to the next vector.
iov++;
}
return nwrite;
}
#endif // EMULATE_WRITEV
static bool
buffer_alloc (const struct config *config, struct buffer *buf)
{
if ((buf->raw = malloc(BUFFER_RAW_SIZE)) == NULL ||
(buf->enc = malloc(BUFFER_ENC_SIZE)) == NULL) {
free(buf->raw);
fprintf(stderr, "%s: malloc: %s\n",
config->name, strerror(errno));
return false;
}
return true;
}
static void
buffer_free (struct buffer *buf)
{
free(buf->raw);
free(buf->enc);
}
static bool
writev_retry (const struct config *config, struct iovec *iov, size_t nvec)
{
// Writing nothing always succeeds.
if (nvec == 0) {
return true;
}
while (true) {
ssize_t nwrite;
// Try to write the vectors to stdout.
if ((nwrite = writev(1, iov, nvec)) < 0) {
// Retry on EINTR.
if (errno == EINTR) {
continue;
}
// Quit on other errors.
fprintf(stderr, "%s: writev: %s\n",
config->name, strerror(errno));
return false;
}
// The return value of `writev' is the number of bytes written.
// To check for success, we traverse the list and remove all
// written vectors. The call succeeded if the list is empty.
while (true) {
// Retry if this vector is not or partially written.
if (iov->iov_len > (size_t) nwrite) {
char *base = iov->iov_base;
iov->iov_base = (size_t) nwrite + base;
iov->iov_len -= (size_t) nwrite;
break;
}
// Move to the next vector.
nwrite -= iov->iov_len;
iov++;
// Return successfully if all vectors were written.
if (--nvec == 0) {
return true;
}
}
}
}
static inline bool
iov_append (const struct config *config, struct iovec *iov,
size_t *nvec, char *base, const size_t len)
{
// Add the buffer to the IO vector array.
iov[*nvec].iov_base = base;
iov[*nvec].iov_len = len;
// Increment the array index. Flush the array if it is full.
if (++(*nvec) == IOV_MAX) {
if (writev_retry(config, iov, IOV_MAX) == false) {
return false;
}
*nvec = 0;
}
return true;
}
static bool
write_stdout (const struct config *config, const char *buf, size_t len)
{
while (len > 0) {
ssize_t nwrite;
// Try to write the buffer to stdout.
if ((nwrite = write(1, buf, len)) < 0) {
// Retry on EINTR.
if (errno == EINTR) {
continue;
}
// Quit on other errors.
fprintf(stderr, "%s: write: %s\n",
config->name, strerror(errno));
return false;
}
// Update the buffer position.
buf += (size_t) nwrite;
len -= (size_t) nwrite;
}
return true;
}
static bool
write_wrapped (const struct config *config, char *buf, size_t len)
{
static size_t col = 0;
// Special case: if buf is NULL, print final trailing newline.
if (buf == NULL) {
if (config->wrap > 0 && col > 0) {
return write_stdout(config, "\n", 1);
}
return true;
}
// If no wrap width is given, write the entire buffer.
if (config->wrap == 0) {
return write_stdout(config, buf, len);
}
// Statically allocated IO vector buffer.
static struct iovec iov[IOV_MAX];
size_t nvec = 0;
while (len > 0) {
// Number of characters to fill the current line.
size_t nwrite = config->wrap - col;
// Do not write more data than is available.
if (nwrite > len) {
nwrite = len;
}
// Append the data to the IO vector array.
if (iov_append(config, iov, &nvec, buf, nwrite) == false) {
return false;
}
// Advance the buffer.
len -= nwrite;
buf += nwrite;
col += nwrite;
// If the line is full, append a newline.
if (col == config->wrap) {
if (iov_append(config, iov, &nvec, "\n", 1) == false) {
return false;
}
col = 0;
}
}
// Write the remaining vectors.
if (writev_retry(config, iov, nvec) == false) {
return false;
}
return true;
}
static bool
encode (const struct config *config, struct buffer *buf)
{
size_t nread, nout;
struct base64_state state;
// Initialize the encoder's state structure.
base64_stream_encode_init(&state, 0);
// Read raw data into the buffer.
while ((nread = fread(buf->raw, 1, BUFFER_RAW_SIZE, config->fp)) > 0) {
// Encode the raw input into the encoded buffer.
base64_stream_encode(&state, buf->raw, nread, buf->enc, &nout);
// Append the encoded data to the output stream.
if (write_wrapped(config, buf->enc, nout) == false) {
return false;
}
}
// Check for stream errors.
if (ferror(config->fp)) {
fprintf(stderr, "%s: %s: read error\n",
config->name, config->file);
return false;
}
// Finalize the encoding by adding proper stream terminators.
base64_stream_encode_final(&state, buf->enc, &nout);
// Append this tail to the output stream.
if (write_wrapped(config, buf->enc, nout) == false) {
return false;
}
// Print optional trailing newline.
if (write_wrapped(config, NULL, 0) == false) {
return false;
}
return true;
}
static inline size_t
find_newline (const char *p, const size_t avail)
{
// This is very naive and can probably be improved by vectorization.
for (size_t len = 0; len < avail; len++) {
if (p[len] == '\n') {
return len;
}
}
return avail;
}
static bool
decode (const struct config *config, struct buffer *buf)
{
size_t avail;
struct base64_state state;
// Initialize the decoder's state structure.
base64_stream_decode_init(&state, 0);
// Read encoded data into the buffer. Use the smallest buffer size to
// be on the safe side: the decoded output will fit the raw buffer.
while ((avail = fread(buf->enc, 1, BUFFER_RAW_SIZE, config->fp)) > 0) {
char *start = buf->enc;
char *outbuf = buf->raw;
size_t ototal = 0;
// By popular demand, this utility tries to be bug-compatible
// with GNU `base64'. That includes silently ignoring newlines
// in the input. Tokenize the input on newline characters.
while (avail > 0) {
// Find the offset of the next newline character, which
// is also the length of the next chunk.
size_t outlen, len = find_newline(start, avail);
// Ignore empty chunks.
if (len == 0) {
start++;
avail--;
continue;
}
// Decode the chunk into the raw buffer.
if (base64_stream_decode(&state, start, len,
outbuf, &outlen) == 0) {
fprintf(stderr, "%s: %s: decoding error\n",
config->name, config->file);
return false;
}
// Update the output buffer pointer and total size.
outbuf += outlen;
ototal += outlen;
// Bail out if the whole string has been consumed.
if (len == avail) {
break;
}
// Move the start pointer past the newline.
start += len + 1;
avail -= len + 1;
}
// Append the raw data to the output stream.
if (write_stdout(config, buf->raw, ototal) == false) {
return false;
}
}
// Check for stream errors.
if (ferror(config->fp)) {
fprintf(stderr, "%s: %s: read error\n",
config->name, config->file);
return false;
}
return true;
}
static void
usage (FILE *fp, const struct config *config)
{
const char *usage =
"Usage: %s [OPTION]... [FILE]\n"
"If no FILE is given or is specified as '-', "
"read from standard input.\n"
"Options:\n"
" -d, --decode Decode a base64 stream.\n"
" -h, --help Print this help text.\n"
" -w, --wrap=COLS Wrap encoded lines at this column. "
"Default 76, 0 to disable.\n";
fprintf(fp, usage, config->name);
}
static bool
get_wrap (struct config *config, const char *str)
{
char *eptr;
// Reject empty strings.
if (*str == '\0') {
return false;
}
// Convert the input string to a signed long.
const long wrap = strtol(str, &eptr, 10);
// Reject negative numbers.
if (wrap < 0) {
return false;
}
// Reject strings containing non-digits.
if (*eptr != '\0') {
return false;
}
config->wrap = (size_t) wrap;
return true;
}
static bool
parse_opts (int argc, char **argv, struct config *config)
{
int c;
static const struct option opts[] = {
{ "decode", no_argument, NULL, 'd' },
{ "help", no_argument, NULL, 'h' },
{ "wrap", required_argument, NULL, 'w' },
{ NULL }
};
// Remember the program's name.
config->name = *argv;
// Parse command line options.
while ((c = getopt_long(argc, argv, ":dhw:", opts, NULL)) != -1) {
switch (c) {
case 'd':
config->decode = true;
break;
case 'h':
config->print_help = true;
return true;
case 'w':
if (get_wrap(config, optarg) == false) {
fprintf(stderr,
"%s: invalid wrap value '%s'\n",
config->name, optarg);
return false;
}
break;
case ':':
fprintf(stderr, "%s: missing argument for '%c'\n",
config->name, optopt);
return false;
default:
fprintf(stderr, "%s: unknown option '%c'\n",
config->name, optopt);
return false;
}
}
// Return successfully if no filename was given.
if (optind >= argc) {
return true;
}
// Return unsuccessfully if more than one filename was given.
if (optind + 1 < argc) {
fprintf(stderr, "%s: too many files\n", config->name);
return false;
}
// For compatibility with GNU Coreutils base64, treat a filename of '-'
// as standard input.
if (strcmp(argv[optind], "-") == 0) {
return true;
}
// Save the name of the file.
config->file = argv[optind];
// Open the file.
if ((config->fp = fopen(config->file, "rb")) == NULL) {
fprintf(stderr, "%s: %s: %s\n",
config->name, config->file, strerror(errno));
return false;
}
return true;
}
int
main (int argc, char **argv)
{
// Default program config.
struct config config = {
.file = "stdin",
.fp = stdin,
.wrap = 76,
.decode = false,
.print_help = false,
};
struct buffer buf;
// Parse options from the command line.
if (parse_opts(argc, argv, &config) == false) {
usage(stderr, &config);
return 1;
}
// Return early if the user just wanted the help text.
if (config.print_help) {
usage(stdout, &config);
return 0;
}
// Allocate buffers.
if (buffer_alloc(&config, &buf) == false) {
return 1;
}
// Encode or decode the input based on the user's choice.
const bool ret = config.decode
? decode(&config, &buf)
: encode(&config, &buf);
// Free the buffers.
buffer_free(&buf);
// Close the input file.
fclose(config.fp);
// Close the output stream.
fclose(stdout);
// That's all, folks.
return ret ? 0 : 1;
}
Mini Shell