mhl/escape.h

   1 #ifndef MHL_ESCAPE_H
   2 #define MHL_ESCAPE_H
   3
   4 /* Micro helper library: shell escaping functions */
   5
   6 #include <string.h>
   7 #include <stdlib.h>
   8 #include <stdbool.h>
   9
  10 #define mhl_shell_escape_toesc(x)       \
  11     (((x)==' ')||((x)=='!')||((x)=='#')||((x)=='$')||((x)=='%')||       \
  12      ((x)=='(')||((x)==')')||((x)=='\'')||((x)=='&')||((x)=='~')||      \
  13      ((x)=='{')||((x)=='}')||((x)=='[')||((x)==']')||((x)=='`')||       \
  14      ((x)=='?')||((x)=='|')||((x)=='<')||((x)=='>')||((x)==';')||       \
  15      ((x)=='*')||((x)=='\\')||((x)=='"'))
  16
  17 #define mhl_shell_escape_nottoesc(x)    \
  18     (((x)!=0) && (!mhl_shell_escape_toesc((x))))
  19
  20 /* type for escaped string - just for a bit more type safety ;-p */
  21 typedef struct { char* s; } SHELL_ESCAPED_STR;
  22
  23 /** To be compatible with the general posix command lines we have to escape
  24  strings for the command line
  25
  26  /params const char * in
  27  string for escaping
  28  /returns
  29  return escaped string (later need to free)
  30  */
  31 static inline SHELL_ESCAPED_STR mhl_shell_escape_dup(const char* src)
  32 {
  33     if ((src==NULL)||(!(*src)))
  34         return (SHELL_ESCAPED_STR){ .s = strdup("") };
  35
  36     char* buffer = calloc(1, strlen(src)*2+2);
  37     char* ptr = buffer;
  38
  39     /* look for the first char to escape */
  40     while (1)
  41     {
  42         char c;
  43         /* copy over all chars not to escape */
  44         while ((c=(*src)) && mhl_shell_escape_nottoesc(c))
  45         {
  46             *ptr = c;
  47             ptr++;
  48             src++;
  49         }
  50
  51         /* at this point we either have an \0 or an char to escape */
  52         if (!c)
  53             return (SHELL_ESCAPED_STR){ .s = buffer };
  54
  55         *ptr = '\\';
  56         ptr++;
  57         *ptr = c;
  58         ptr++;
  59         src++;
  60     }
  61 }
  62
  63 /** Unescape paths or other strings for e.g the internal cd
  64     shell-unescape within a given buffer (writing to it!)
  65
  66  /params const char * src
  67  string for unescaping
  68  /returns
  69  return unescaped string
  70 */
  71 static inline char* mhl_shell_unescape_buf(char* text)
  72 {
  73     if (!text)
  74         return NULL;
  75
  76     /* look for the first \ - that's quick skipover if there's nothing to escape */
  77     char* readptr = text;
  78     while ((*readptr) && ((*readptr)!='\\'))    readptr++;
  79     if (!(*readptr)) return text;
  80
  81     /* if we're here, we're standing on the first '\' */
  82     char* writeptr = readptr;
  83     char c;
  84     while ((c = *readptr))
  85     {
  86         if (c=='\\')
  87         {
  88             readptr++;
  89             switch ((c = *readptr))
  90             {
  91                 case 'n':       (*writeptr) = '\n'; writeptr++; break;
  92                 case 'r':       (*writeptr) = '\r'; writeptr++; break;
  93                 case 't':       (*writeptr) = '\t'; writeptr++; break;
  94
  95                 case ' ':
  96                 case '\\':
  97                 case '#':
  98                 case '$':
  99                 case '%':
 100                 case '(':
 101                 case ')':
 102                 case '[':
 103                 case ']':
 104                 case '{':
 105                 case '}':
 106                 case '<':
 107                 case '>':
 108                 case '!':
 109                 case '*':
 110                 case '?':
 111                 case '~':
 112                 case '`':
 113                 case '"':
 114                 case ';':
 115                 case '\0': /* end of string! malformed escape string */
 116                     goto out;
 117                 default:
 118                     (*writeptr) = c; writeptr++; break;
 119             }
 120         }
 121         else    /* got a normal character */
 122         {
 123             (*writeptr) = *readptr;
 124             writeptr++;
 125         }
 126         readptr++;
 127     }
 128 out:
 129     *writeptr = 0;
 130
 131     return text;
 132 }
 133
 134 /** Check if char in pointer contain escape'd chars
 135
 136  /params const char * in
 137  string for checking
 138  /returns
 139  return TRUE if string contain escaped chars
 140  otherwise return FALSE
 141  */
 142 static inline bool
 143 mhl_shell_is_char_escaped ( const char *in )
 144 {
 145     if (in == NULL || !*in || in[0] != '\\')
 146         return false;
 147     if (mhl_shell_escape_toesc(in[1]))
 148         return true;
 149     return false;
 150 }
 151
 152 #endif