SELinux denials include hex-encoded paths in the log messages; xxd -r -p is a convenient way to decode them.
The heuristics are a little weird to my mind, but match the documentation and observed behavior. --- tests/xxd.test | 19 ++++++++++++++ toys/other/xxd.c | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++----- 2 files changed, 92 insertions(+), 7 deletions(-)
From 29da8c6a616c12cb883879d5d97de9efbe8de24a Mon Sep 17 00:00:00 2001 From: Elliott Hughes <[email protected]> Date: Thu, 18 Feb 2016 21:11:07 -0800 Subject: [PATCH] Add xxd -p and -r. SELinux denials include hex-encoded paths in the log messages; xxd -r -p is a convenient way to decode them. The heuristics are a little weird to my mind, but match the documentation and observed behavior. --- tests/xxd.test | 19 ++++++++++++++ toys/other/xxd.c | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++----- 2 files changed, 92 insertions(+), 7 deletions(-) diff --git a/tests/xxd.test b/tests/xxd.test index e036865..68f52be 100644 --- a/tests/xxd.test +++ b/tests/xxd.test @@ -25,4 +25,23 @@ testing "xxd -c 8 -g 4 file1" "xxd -c 8 -g 4 file1" \ testing "xxd -c 8 -g 3 file1" "xxd -c 8 -g 3 file1" \ "00000000: 746869 732069 7320 this is \n00000008: 736f6d 652074 6578 some tex\n00000010: 740a t.\n" "" "" +testing "xxd -p" "xxd -p file1" "7468697320697320736f6d6520746578740a\n" "" "" + +testing "xxd -r" "xxd file1 | xxd -r" "this is some text\n" "" "" +testing "xxd -r -p" "xxd -p file1 | xxd -r -p" "this is some text\n" "" "" + +testing "xxd -r garbage" "echo '0000: 68 65 6c6c 6fxxxx' | xxd -r -" "hello" "" "" + +# -r will only read -c bytes (default 16) before skipping to the next line, +# ignoring the rest. +testing "xxd -r long" \ + "echo '0000: 40404040404040404040404040404040404040404040404040404040404040404040404040404040' | xxd -r -" \ + "@@@@@@@@@@@@@@@@" "" "" + +# -r -p ignores the usual -p 30-byte/line limit (or any limit set by -c) and +# will take as many bytes as you give it. +testing "xxd -r -p long" \ + "echo '40404040404040404040404040404040404040404040404040404040404040404040404040404040' | xxd -r -p -" \ + "@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@" "" "" + rm file1 file2 diff --git a/toys/other/xxd.c b/toys/other/xxd.c index e9ad839..0250f8f 100644 --- a/toys/other/xxd.c +++ b/toys/other/xxd.c @@ -8,13 +8,13 @@ * TODO: support for reversing a hexdump back into the original data. * TODO: -s seek -USE_XXD(NEWTOY(xxd, ">1c#<1>4096=16l#g#<1=2", TOYFLAG_USR|TOYFLAG_BIN)) +USE_XXD(NEWTOY(xxd, ">1c#<1>4096=16l#g#<1=2pr", TOYFLAG_USR|TOYFLAG_BIN)) config XXD bool "xxd" default y help - usage: xxd [-c n] [-g n] [-l n] [file] + usage: xxd [-c n] [-g n] [-l n] [-p] [-r] [file] Hexdump a file to stdout. If no file is listed, copy from stdin. Filename "-" is a synonym for stdin. @@ -22,6 +22,8 @@ config XXD -c n Show n bytes per line (default 16). -g n Group bytes by adding a ' ' every n bytes (default 2). -l n Limit of n bytes before stopping (default is no limit). + -p Plain hexdump (30 bytes/line, no grouping). + -r Reverse operation: turn a hexdump into a binary file. */ #define FOR_xxd @@ -39,7 +41,7 @@ static void do_xxd(int fd, char *name) int i, len, space; while (0<(len = readall(fd, toybuf, (TT.l && TT.l-pos<TT.c)?TT.l-pos:TT.c))) { - printf("%08llx: ", pos); + if (!(toys.optflags&FLAG_p)) printf("%08llx: ", pos); pos += len; space = 2*TT.c+TT.c/TT.g+1; @@ -51,15 +53,79 @@ static void do_xxd(int fd, char *name) } } - printf("%*s", space, ""); - for (i=0; i<len; i++) - putchar((toybuf[i]>=' ' && toybuf[i]<='~') ? toybuf[i] : '.'); + 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 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"); + + while (!feof(fp)) { + int col = 0; + int tmp; + + // Each line of a non-plain hexdump starts with an offset/address. + 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) { - loopfiles(toys.optargs, do_xxd); + // 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 : do_xxd); } -- 2.7.0.rc3.207.g0ac5344
_______________________________________________ Toybox mailing list [email protected] http://lists.landley.net/listinfo.cgi/toybox-landley.net
