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/*
* escape_ansi.c
* -------------
* Functions for escaping non-printable characters.
*
*
* Copyright 2008, 2009 Sebastien Aperghis-Tramoni
*
* This program is free software; you can redistribute it
* and/or modify it under the same terms as Perl itself.
*/
/* standard includes */
#include <stdlib.h>
/* custom includes */
#include "escape_chars.h"
/* private macros */
#define NON_PRINTABLE(x) ((x) <= '\x1F' || (x) == '\x7F')
#define CHAR_INDEX(x) ( (x) <= '\x1F' ? (int)((x) - '\x00') \
: (x) == '\x7F' ? (int)((x) - '\x1F' + 1) \
: (int)((x) - '\x1F' + 2) )
/* structures */
struct {
const char code;
const char *name;
} charname[] = {
{ '\x00', "NUL" }, /* "\\0" */
{ '\x01', "SOH" },
{ '\x02', "STX" },
{ '\x03', "ETX" },
{ '\x04', "EOT" },
{ '\x05', "ENQ" },
{ '\x06', "ACK" },
{ '\x07', "BEL" }, /* "\\a" */
{ '\x08', "BS" }, /* "\\b" */
{ '\x09', "HT" }, /* "\\t" */
{ '\x0A', "LF" }, /* "\\n" */
{ '\x0B', "VT" }, /* "\\v" */
{ '\x0C', "FF" }, /* "\\f" */
{ '\x0D', "CR" }, /* "\\r" */
{ '\x0E', "SO" },
{ '\x0F', "SI" },
{ '\x10', "DLE" },
{ '\x11', "DC1" },
{ '\x12', "DC2" },
{ '\x13', "DC3" },
{ '\x14', "DC4" },
{ '\x15', "NAK" },
{ '\x16', "SYN" },
{ '\x17', "ETB" },
{ '\x18', "CAN" },
{ '\x19', "EM" },
{ '\x1A', "SUB" },
{ '\x1B', "ESC" },
{ '\x1C', "FS" },
{ '\x1D', "GS" },
{ '\x1E', "RS" },
{ '\x1F', "US" },
{ '\x7F', "DEL" },
{ 0, "???" },
};
/*
* escape_non_printable_chars()
* --------------------------
/*! Escape non-printable characters
*
* This function parse the given null-terminated string and looks for
* non-printable characters to escape.
*
* If there are any, a new string is allocated where each non-printable
* character is replaced with a human-readable representation. For example
* the character '\x1B' (ESC) is replace with "<ESC>".
*
* If there is no character to escape, the original string is returned.
*
* Typical usage:
*
* char input[] = "";
* char *output;
*
* output = escape_non_printable_chars(input);
* ...
* if (output != input)
* free(output);
*
*
* @param input null-terminated string
* @return null-terminated string
*
*/
char * escape_non_printable_chars(const char *input) {
char *output;
const char *i;
const char *n;
char *o;
int len = 0;
int num = 0;
/* first loop to calculate the number of characters to escape */
for (i=input; *i != '\0'; i++) {
len++;
if (NON_PRINTABLE(*i))
num++;
}
/* if there's nothing to escape, just return the input string */
if (num == 0)
return (char *) input;
output = (char *) malloc(len + 4*num);
/* second loop to actually escape the non-printable characters */
for (i=input, o=output; *i != '\0'; i++) {
if (NON_PRINTABLE(*i)) {
*o++ = '<';
for (n=charname[CHAR_INDEX(*i)].name; *n != '\0'; n++)
*o++ = *n;
*o++ = '>';
}
else
*o++ = *i;
}
*o = '\0';
return output;
}