Return to HTEscape.c CVS log

Up to [Public] / libwww / Library / src

Annotation of libwww/Library/src/HTEscape.c, revision 2.14

2.2       frystyk     1: /*                                                                  HTEscape.c
                      2: **     ESCAPE AND UNESACPE ILLEGAL CHARACTERS IN A URI
                      3: **
2.5       frystyk     4: **     (c) COPYRIGHT MIT 1995.
2.2       frystyk     5: **     Please first read the full copyright statement in the file COPYRIGH.
2.14    ! frystyk     6: **     @(#) $Id: Date Author State $
2.1       frystyk     7: **
                      8: ** history:
                      9: **     Nov 13 94       Spawned from HTParse, as it then can be used in utility
                     10: **                     programs without loading the whole library
                     11: */
                     12: 
2.4       frystyk    13: /* Library include files */
2.13      frystyk    14: #include "sysdep.h"
2.1       frystyk    15: #include "HTUtils.h"
                     16: #include "HTEscape.h"                                   /* Implemented here */
                     17: 
                     18: #define HEX_ESCAPE '%'
2.6       frystyk    19: #define ACCEPTABLE(a)  ( a>=32 && a<128 && ((isAcceptable[a-32]) & mask))
                     20: 
                     21: /*
2.13      frystyk    22: **  Not BOTH static AND const at the same time in gcc :-(, Henrik 18/03-94 
                     23: **  code gen error in gcc when making random access to static const table(!!)
2.6       frystyk    24: */
                     25: 
                     26: /*
                     27: **     Bit 0           xalpha          -- see HTFile.h
                     28: **     Bit 1           xpalpha         -- as xalpha but with plus.
                     29: **     Bit 2 ...       path            -- as xpalpha but with /
                     30: */
                     31: PRIVATE unsigned char isAcceptable[96] =
                     32: {/* 0 1 2 3 4 5 6 7 8 9 A B C D E F */
                     33:     0,0,0,0,0,0,0,0,0,0,7,6,0,7,7,4,           /* 2x   !"#$%&'()*+,-./  */
                     34:     7,7,7,7,7,7,7,7,7,7,0,0,0,0,0,0,           /* 3x  0123456789:;<=>?  */
                     35:     7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,           /* 4x  @ABCDEFGHIJKLMNO  */
                     36:     7,7,7,7,7,7,7,7,7,7,7,0,0,0,0,7,           /* 5X  PQRSTUVWXYZ[\]^_  */
                     37:     0,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,           /* 6x  `abcdefghijklmno  */
                     38:     7,7,7,7,7,7,7,7,7,7,7,0,0,0,0,0            /* 7X  pqrstuvwxyz{\}~  DEL */
                     39: };
                     40: PRIVATE char *hex = "0123456789ABCDEF";
2.1       frystyk    41: 
                     42: /* ------------------------------------------------------------------------- */
                     43: 
                     44: /*             Escape undesirable characters using %           HTEscape()
                     45: **             -------------------------------------
                     46: **
                     47: **     This function takes a pointer to a string in which
                     48: **     some characters may be unacceptable unescaped.
                     49: **     It returns a string which has these characters
                     50: **     represented by a '%' character followed by two hex digits.
                     51: **
                     52: **     In the tradition of being conservative in what you do and liberal
                     53: **     in what you accept, we encode some characters which in fact are
                     54: **     allowed in URLs unencoded -- so DON'T use the table below for
                     55: **     parsing! 
                     56: **
2.13      frystyk    57: **     Unlike HTUnEscape(), this routine returns a HT_MALLOCed string.
2.1       frystyk    58: **
                     59: */
2.13      frystyk    60: PUBLIC char * HTEscape (const char * str, HTURIEncoding mask)
2.1       frystyk    61: {
2.13      frystyk    62:     const char * p;
2.1       frystyk    63:     char * q;
                     64:     char * result;
                     65:     int unacceptable = 0;
                     66:     for(p=str; *p; p++)
                     67:         if (!ACCEPTABLE((unsigned char)TOASCII(*p)))
                     68:                unacceptable++;
2.11      frystyk    69:     if ((result = (char  *) HT_MALLOC(p-str + unacceptable+ unacceptable + 1)) == NULL)
                     70:         HT_OUTOFMEM("HTEscape");
2.1       frystyk    71:     for(q=result, p=str; *p; p++) {
                     72:        unsigned char a = TOASCII(*p);
                     73:        if (!ACCEPTABLE(a)) {
                     74:            *q++ = HEX_ESCAPE;  /* Means hex commming */
                     75:            *q++ = hex[a >> 4];
                     76:            *q++ = hex[a & 15];
                     77:        }
                     78:        else *q++ = *p;
                     79:     }
                     80:     *q++ = 0;                  /* Terminate */
                     81:     return result;
                     82: }
                     83: 
                     84: 
                     85: /*             Decode %xx escaped characters                   HTUnEscape()
                     86: **             -----------------------------
                     87: **
                     88: **     This function takes a pointer to a string in which some
                     89: **     characters may have been encoded in %xy form, where xy is
                     90: **     the acsii hex code for character 16x+y.
                     91: **     The string is converted in place, as it will never grow.
                     92: */
                     93: 
2.9       frystyk    94: PRIVATE char from_hex (char c)
2.1       frystyk    95: {
                     96:     return  c >= '0' && c <= '9' ?  c - '0' 
                     97:            : c >= 'A' && c <= 'F'? c - 'A' + 10
                     98:            : c - 'a' + 10;     /* accept small letters just in case */
                     99: }
                    100: 
2.9       frystyk   101: PUBLIC char * HTUnEscape (char * str)
2.1       frystyk   102: {
                    103:     char * p = str;
                    104:     char * q = str;
                    105: 
                    106:     if (!str) {                                              /* Just for safety ;-) */
                    107:        if (URI_TRACE)
2.12      eric      108:            HTTrace("HTUnEscape.. Called with NULL argument.\n");
2.1       frystyk   109:        return "";
                    110:     }
                    111:     while(*p) {
                    112:         if (*p == HEX_ESCAPE) {
                    113:            p++;
                    114:            if (*p) *q = from_hex(*p++) * 16;
2.7       frystyk   115:            if (*p) *q = FROMASCII(*q + from_hex(*p));
                    116:            p++, q++;
2.1       frystyk   117:        } else {
                    118:            *q++ = *p++; 
                    119:        }
                    120:     }
                    121:     
                    122:     *q++ = 0;
                    123:     return str;
                    124:     
                    125: } /* HTUnEscape */
                    126: