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 #define Py_USE_NEW_NAMES 1
  43
  44 #include "config.h"
  45
  46 #include <stdio.h>
  47 #include <string.h>
  48 #include <errno.h>
  49
  50 #include "myproto.h"
  51 #include "mymalloc.h"
  52 #include "intrcheck.h"
  53
  54 int (*PyOS_InputHook)() = NULL;
  55
  56 /* This function restarts a fgets() after an EINTR error occurred
  57    except if PyOS_InterruptOccurred() returns true. */
  58
  59 static int
  60 my_fgets(buf, len, fp)
  61         char *buf;
  62         int len;
  63         FILE *fp;
  64 {
  65         char *p;
  66         for (;;) {
  67                 if (PyOS_InputHook != NULL)
  68                         (void)(PyOS_InputHook)();
  69                 errno = 0;
  70                 p = fgets(buf, len, fp);
  71                 if (p != NULL)
  72                         return 0; /* No error */
  73                 if (feof(fp)) {
  74                         return -1; /* EOF */
  75                 }
  76 #ifdef EINTR
  77                 if (errno == EINTR) {
  78                         if (PyOS_InterruptOccurred()) {
  79                                 return 1; /* Interrupt */
  80                         }
  81                         continue;
  82                 }
  83 #endif
  84                 if (PyOS_InterruptOccurred()) {
  85                         return 1; /* Interrupt */
  86                 }
  87                 return -2; /* Error */
  88         }
  89         /* NOTREACHED */
  90 }
  91
  92
  93 /* Readline implementation using fgets() */
  94
  95 char *
  96 PyOS_StdioReadline(prompt)
  97         char *prompt;
  98 {
  99         int n;
 100         char *p;
 101         n = 100;
 102         if ((p = malloc(n)) == NULL)
 103                 return NULL;
 104         fflush(stdout);
 105         if (prompt)
 106                 fprintf(stderr, "%s", prompt);
 107         fflush(stderr);
 108         switch (my_fgets(p, n, stdin)) {
 109         case 0: /* Normal case */
 110                 break;
 111         case 1: /* Interrupt */
 112                 free(p);
 113                 return NULL;
 114         case -1: /* EOF */
 115         case -2: /* Error */
 116         default: /* Shouldn't happen */
 117                 *p = '\0';
 118                 break;
 119         }
 120 #ifdef MPW
 121         /* Hack for MPW C where the prompt comes right back in the input */
 122         /* XXX (Actually this would be rather nice on most systems...) */
 123         n = strlen(prompt);
 124         if (strncmp(p, prompt, n) == 0)
 125                 memmove(p, p + n, strlen(p) - n + 1);
 126 #endif
 127         n = strlen(p);
 128         while (n > 0 && p[n-1] != '\n') {
 129                 int incr = n+2;
 130                 p = realloc(p, n + incr);
 131                 if (p == NULL)
 132                         return NULL;
 133                 if (my_fgets(p+n, incr, stdin) != 0)
 134                         break;
 135                 n += strlen(p+n);
 136         }
 137         return realloc(p, n+1);
 138 }
 139
 140
 141 /* By initializing this function pointer, systems embedding Python can
 142    override the readline function. */
 143
 144 char *(*PyOS_ReadlineFunctionPointer) Py_PROTO((char *));
 145
 146
 147 /* Interface used by tokenizer.c and bltinmodule.c */
 148
 149 char *
 150 PyOS_Readline(prompt)
 151         char *prompt;
 152 {
 153         if (PyOS_ReadlineFunctionPointer == NULL) {
 154                         PyOS_ReadlineFunctionPointer = PyOS_StdioReadline;
 155         }
 156         return (*PyOS_ReadlineFunctionPointer)(prompt);
 157 }