toys/other/xxd.c

/* xxd.c - hexdump.
 *
 * Copyright 2015 The Android Open Source Project
 *
 * No obvious standard.
 * Regular output:
 *   "00000000: 4c69 6e75 7820 7665 7273 696f 6e20 342e  Linux version 4."
 * xxd -i "include" or "initializer" output:
 *   "  0x4c, 0x69, 0x6e, 0x75, 0x78, 0x20, 0x76, 0x65, 0x72, 0x73, 0x69, 0x6f,"
 * xxd -p "plain" output:
 *   "4c696e75782076657273696f6e20342e392e302d342d616d643634202864"

USE_XXD(NEWTOY(xxd, ">1c#l#o#g#<1=2iprs#[!rs]", TOYFLAG_USR|TOYFLAG_BIN))

config XXD
  bool "xxd"
  default y
  help
    usage: xxd [-c n] [-g n] [-i] [-l n] [-o n] [-p] [-r] [-s n] [file]

    Hexdump a file to stdout.  If no file is listed, copy from stdin.
    Filename "-" is a synonym for stdin.

    -c n	Show n bytes per line (default 16)
    -g n	Group bytes by adding a ' ' every n bytes (default 2)
    -i	Include file output format (comma-separated hex byte literals)
    -l n	Limit of n bytes before stopping (default is no limit)
    -o n	Add n to display offset
    -p	Plain hexdump (30 bytes/line, no grouping)
    -r	Reverse operation: turn a hexdump into a binary file
    -s n	Skip to offset n
*/

#define FOR_xxd
#include "toys.h"

GLOBALS(
  long s, g, o, l, c;
)

static void do_xxd(int fd, char *name)
{
  long long pos = 0;
  long long limit = TT.l;
  int i, len, space;

  if (toys.optflags&FLAG_s) {
    xlseek(fd, TT.s, SEEK_SET);
    pos = TT.s;
    if (limit) limit += TT.s;
  }

  while (0<(len = readall(fd, toybuf,
                          (limit && limit-pos<TT.c)?limit-pos:TT.c))) {
    if (!(toys.optflags&FLAG_p)) printf("%08llx: ", TT.o + pos);
    pos += len;
    space = 2*TT.c+TT.c/TT.g+1;

    for (i=0; i<len;) {
      space -= printf("%02x", toybuf[i]);
      if (!(++i%TT.g)) {
        putchar(' ');
        space--;
      }
    }

    if (!(toys.optflags&FLAG_p)) {
      printf("%*s", space, "");
      for (i=0; i<len; i++)
        putchar((toybuf[i]>=' ' && toybuf[i]<='~') ? toybuf[i] : '.');
    }
    putchar('\n');
  }
  if (len<0) perror_exit("read");
}

static void do_xxd_include(int fd, char *name)
{
  long long total = 0;
  int c = 1, i, len;

  // The original xxd outputs a header/footer if given a filename (not stdin).
  // We don't, which means that unlike the original we can implement -ri.
  while ((len = read(fd, toybuf, sizeof(toybuf))) > 0) {
    total += len;
    for (i = 0; i < len; ++i) {
      printf("%s%#.02x", c > 1 ? ", " : "  ", toybuf[i]);
      if (c++ == TT.c) {
        xprintf(",\n");
        c = 1;
      }
    }
  }
  if (len < 0) perror_msg_raw(name);
  if (c > 1) xputc('\n');
}

static int dehex(char ch)
{
  if (ch >= '0' && ch <= '9') return ch - '0';
  if (ch >= 'a' && ch <= 'f') return ch - 'a' + 10;
  if (ch >= 'A' && ch <= 'F') return ch - 'A' + 10;
  return (ch == '\n') ? -2 : -1;
}

static void do_xxd_reverse(int fd, char *name)
{
  FILE *fp = xfdopen(fd, "r");
  int tmp;

  if (toys.optflags&FLAG_i) {
    // -ri is a very easy special case.
    while (fscanf(fp, " 0x%02x,", &tmp) == 1) {
      fputc(tmp & 0xff, stdout);
    }
  } else {
    while (!feof(fp)) {
      int col = 0;

      // Each line of a regular hexdump starts with an offset/address.
      // Each line of a plain hexdump just goes straight into the bytes.
      if (!(toys.optflags&FLAG_p)) {
        long long pos;

        if (fscanf(fp, "%llx: ", &pos) == 1) {
          if (fseek(stdout, pos, SEEK_SET) != 0) {
            // TODO: just write out zeros if non-seekable?
            perror_exit("%s: seek failed", name);
          }
        }
      }

      // A plain hexdump can have as many bytes per line as you like,
      // but a non-plain hexdump assumes garbage after it's seen the
      // specified number of bytes.
      while (toys.optflags&FLAG_p || col < TT.c) {
        int n1, n2;

        // If we're at EOF or EOL or we read some non-hex...
        if ((n1 = n2 = dehex(fgetc(fp))) < 0 || (n2 = dehex(fgetc(fp))) < 0) {
          // If we're at EOL, start on that line.
          if (n1 == -2 || n2 == -2) continue;
          // Otherwise, skip to the next line.
          break;
        }

        fputc((n1 << 4) | (n2 & 0xf), stdout);
        col++;

        // Is there any grouping going on? Ignore a single space.
        tmp = fgetc(fp);
        if (tmp != ' ') ungetc(tmp, fp);
      }

      // Skip anything else on this line (such as the ASCII dump).
      while ((tmp = fgetc(fp)) != EOF && tmp != '\n')
        ;
    }
  }

  if (ferror(fp)) perror_msg_raw(name);
  fclose(fp);
}

void xxd_main(void)
{
  if (TT.c < 0 || TT.c > 256) error_exit("invalid -c: %ld", TT.c);
  if (TT.c == 0) TT.c = (toys.optflags&FLAG_i)?12:16;

  // Plain style is 30 bytes/line, no grouping.
  if (toys.optflags&FLAG_p) TT.c = TT.g = 30;

  loopfiles(toys.optargs,
    toys.optflags&FLAG_r ? do_xxd_reverse
      : (toys.optflags&FLAG_i ? do_xxd_include : do_xxd));
}