Parser/myreadline.c

   1 /***********************************************************
   2 Copyright 1991-1995 by Stichting Mathematisch Centrum, Amsterdam,
   3 The Netherlands.
   4
   5                         All Rights Reserved
   6
   7 Permission to use, copy, modify, and distribute this software and its
   8 documentation for any purpose and without fee is hereby granted,
   9 provided that the above copyright notice appear in all copies and that
  10 both that copyright notice and this permission notice appear in
  11 supporting documentation, and that the names of Stichting Mathematisch
  12 Centrum or CWI or Corporation for National Research Initiatives or
  13 CNRI not be used in advertising or publicity pertaining to
  14 distribution of the software without specific, written prior
  15 permission.
  16
  17 While CWI is the initial source for this software, a modified version
  18 is made available by the Corporation for National Research Initiatives
  19 (CNRI) at the Internet address ftp://ftp.python.org.
  20
  21 STICHTING MATHEMATISCH CENTRUM AND CNRI DISCLAIM ALL WARRANTIES WITH
  22 REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF
  23 MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH
  24 CENTRUM OR CNRI BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
  25 DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  26 PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
  27 TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  28 PERFORMANCE OF THIS SOFTWARE.
  29
  30 ******************************************************************/
  31
  32 /* Readline interface for tokenizer.c and [raw_]input() in bltinmodule.c.
  33    By default, or when stdin is not a tty device, we have a super
  34    simple my_readline function using fgets.
  35    Optionally, we can use the GNU readline library.
  36    my_readline() has a different return value from GNU readline():
  37    - NULL if an interrupt occurred or if an error occurred
  38    - a malloc'ed empty string if EOF was read
  39    - a malloc'ed string ending in \n normally
  40 */
  41
  42 #include "Python.h"
  43
  44 int (*PyOS_InputHook)() = NULL;
  45
  46 /* This function restarts a fgets() after an EINTR error occurred
  47    except if PyOS_InterruptOccurred() returns true. */
  48
  49 static int
  50 my_fgets(buf, len, fp)
  51         char *buf;
  52         int len;
  53         FILE *fp;
  54 {
  55         char *p;
  56         for (;;) {
  57                 if (PyOS_InputHook != NULL)
  58                         (void)(PyOS_InputHook)();
  59                 errno = 0;
  60                 p = fgets(buf, len, fp);
  61                 if (p != NULL)
  62                         return 0; /* No error */
  63                 if (feof(fp)) {
  64                         return -1; /* EOF */
  65                 }
  66 #ifdef EINTR
  67                 if (errno == EINTR) {
  68                         if (PyOS_InterruptOccurred()) {
  69                                 return 1; /* Interrupt */
  70                         }
  71                         continue;
  72                 }
  73 #endif
  74                 if (PyOS_InterruptOccurred()) {
  75                         return 1; /* Interrupt */
  76                 }
  77                 return -2; /* Error */
  78         }
  79         /* NOTREACHED */
  80 }
  81
  82
  83 /* Readline implementation using fgets() */
  84
  85 char *
  86 PyOS_StdioReadline(prompt)
  87         char *prompt;
  88 {
  89         int n;
  90         char *p;
  91         n = 100;
  92         if ((p = malloc(n)) == NULL)
  93                 return NULL;
  94         fflush(stdout);
  95         if (prompt)
  96                 fprintf(stderr, "%s", prompt);
  97         fflush(stderr);
  98         switch (my_fgets(p, n, stdin)) {
  99         case 0: /* Normal case */
 100                 break;
 101         case 1: /* Interrupt */
 102                 free(p);
 103                 return NULL;
 104         case -1: /* EOF */
 105         case -2: /* Error */
 106         default: /* Shouldn't happen */
 107                 *p = '\0';
 108                 break;
 109         }
 110 #ifdef MPW
 111         /* Hack for MPW C where the prompt comes right back in the input */
 112         /* XXX (Actually this would be rather nice on most systems...) */
 113         n = strlen(prompt);
 114         if (strncmp(p, prompt, n) == 0)
 115                 memmove(p, p + n, strlen(p) - n + 1);
 116 #endif
 117         n = strlen(p);
 118         while (n > 0 && p[n-1] != '\n') {
 119                 int incr = n+2;
 120                 p = realloc(p, n + incr);
 121                 if (p == NULL)
 122                         return NULL;
 123                 if (my_fgets(p+n, incr, stdin) != 0)
 124                         break;
 125                 n += strlen(p+n);
 126         }
 127         return realloc(p, n+1);
 128 }
 129
 130
 131 /* By initializing this function pointer, systems embedding Python can
 132    override the readline function. */
 133
 134 char *(*PyOS_ReadlineFunctionPointer) Py_PROTO((char *));
 135
 136
 137 /* Interface used by tokenizer.c and bltinmodule.c */
 138
 139 char *
 140 PyOS_Readline(prompt)
 141         char *prompt;
 142 {
 143         char *rv;
 144         if (PyOS_ReadlineFunctionPointer == NULL) {
 145                         PyOS_ReadlineFunctionPointer = PyOS_StdioReadline;
 146         }
 147         Py_BEGIN_ALLOW_THREADS
 148         rv = (*PyOS_ReadlineFunctionPointer)(prompt);
 149         Py_END_ALLOW_THREADS
 150         return rv;
 151 }