summaryrefslogtreecommitdiffstats
path: root/Parser/myreadline.c
blob: 28c7b6d7fff83c2c1d0f6421ef8a364abda5fa6f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231

/* Readline interface for tokenizer.c and [raw_]input() in bltinmodule.c.
   By default, or when stdin is not a tty device, we have a super
   simple my_readline function using fgets.
   Optionally, we can use the GNU readline library.
   my_readline() has a different return value from GNU readline():
   - NULL if an interrupt occurred or if an error occurred
   - a malloc'ed empty string if EOF was read
   - a malloc'ed string ending in \n normally
*/

#include "Python.h"
#ifdef MS_WINDOWS
#define WIN32_LEAN_AND_MEAN
#include "windows.h"
#endif /* MS_WINDOWS */


PyThreadState* _PyOS_ReadlineTState;

#ifdef WITH_THREAD
#include "pythread.h"
static PyThread_type_lock _PyOS_ReadlineLock = NULL;
#endif

int (*PyOS_InputHook)(void) = NULL;

/* This function restarts a fgets() after an EINTR error occurred
   except if PyOS_InterruptOccurred() returns true. */

static int
my_fgets(char *buf, int len, FILE *fp)
{
#ifdef MS_WINDOWS
    HANDLE hInterruptEvent;
#endif
    char *p;
    int err;
    while (1) {
        if (PyOS_InputHook != NULL)
            (void)(PyOS_InputHook)();
        errno = 0;
        clearerr(fp);
        if (_PyVerify_fd(fileno(fp)))
            p = fgets(buf, len, fp);
        else
            p = NULL;
        if (p != NULL)
            return 0; /* No error */
        err = errno;
#ifdef MS_WINDOWS
        /* Ctrl-C anywhere on the line or Ctrl-Z if the only character
           on a line will set ERROR_OPERATION_ABORTED. Under normal
           circumstances Ctrl-C will also have caused the SIGINT handler
           to fire which will have set the event object returned by
           _PyOS_SigintEvent. This signal fires in another thread and
           is not guaranteed to have occurred before this point in the
           code.

           Therefore: check whether the event is set with a small timeout.
           If it is, assume this is a Ctrl-C and reset the event. If it
           isn't set assume that this is a Ctrl-Z on its own and drop
           through to check for EOF.
        */
        if (GetLastError()==ERROR_OPERATION_ABORTED) {
            hInterruptEvent = _PyOS_SigintEvent();
            switch (WaitForSingleObjectEx(hInterruptEvent, 10, FALSE)) {
            case WAIT_OBJECT_0:
                ResetEvent(hInterruptEvent);
                return 1; /* Interrupt */
            case WAIT_FAILED:
                return -2; /* Error */
            }
        }
#endif /* MS_WINDOWS */
        if (feof(fp)) {
            clearerr(fp);
            return -1; /* EOF */
        }
#ifdef EINTR
        if (err == EINTR) {
            int s;
#ifdef WITH_THREAD
            PyEval_RestoreThread(_PyOS_ReadlineTState);
#endif
            s = PyErr_CheckSignals();
#ifdef WITH_THREAD
            PyEval_SaveThread();
#endif
            if (s < 0)
                    return 1;
        /* try again */
            continue;
        }
#endif
        if (PyOS_InterruptOccurred()) {
            return 1; /* Interrupt */
        }
        return -2; /* Error */
    }
    /* NOTREACHED */
}


/* Readline implementation using fgets() */

char *
PyOS_StdioReadline(FILE *sys_stdin, FILE *sys_stdout, const char *prompt)
{
    size_t n;
    char *p, *pr;

    n = 100;
    p = (char *)PyMem_RawMalloc(n);
    if (p == NULL)
        return NULL;

    fflush(sys_stdout);
    if (prompt)
        fprintf(stderr, "%s", prompt);
    fflush(stderr);

    switch (my_fgets(p, (int)n, sys_stdin)) {
    case 0: /* Normal case */
        break;
    case 1: /* Interrupt */
        PyMem_RawFree(p);
        return NULL;
    case -1: /* EOF */
    case -2: /* Error */
    default: /* Shouldn't happen */
        *p = '\0';
        break;
    }
    n = strlen(p);
    while (n > 0 && p[n-1] != '\n') {
        size_t incr = n+2;
        if (incr > INT_MAX) {
            PyMem_RawFree(p);
            PyErr_SetString(PyExc_OverflowError, "input line too long");
            return NULL;
        }
        pr = (char *)PyMem_RawRealloc(p, n + incr);
        if (pr == NULL) {
            PyMem_RawFree(p);
            PyErr_NoMemory();
            return NULL;
        }
        p = pr;
        if (my_fgets(p+n, (int)incr, sys_stdin) != 0)
            break;
        n += strlen(p+n);
    }
    pr = (char *)PyMem_RawRealloc(p, n+1);
    if (pr == NULL) {
        PyMem_RawFree(p);
        PyErr_NoMemory();
        return NULL;
    }
    return pr;
}


/* By initializing this function pointer, systems embedding Python can
   override the readline function.

   Note: Python expects in return a buffer allocated with PyMem_Malloc. */

char *(*PyOS_ReadlineFunctionPointer)(FILE *, FILE *, const char *);


/* Interface used by tokenizer.c and bltinmodule.c */

char *
PyOS_Readline(FILE *sys_stdin, FILE *sys_stdout, const char *prompt)
{
    char *rv, *res;
    size_t len;

    if (_PyOS_ReadlineTState == PyThreadState_GET()) {
        PyErr_SetString(PyExc_RuntimeError,
                        "can't re-enter readline");
        return NULL;
    }


    if (PyOS_ReadlineFunctionPointer == NULL) {
        PyOS_ReadlineFunctionPointer = PyOS_StdioReadline;
    }

#ifdef WITH_THREAD
    if (_PyOS_ReadlineLock == NULL) {
        _PyOS_ReadlineLock = PyThread_allocate_lock();
    }
#endif

    _PyOS_ReadlineTState = PyThreadState_GET();
    Py_BEGIN_ALLOW_THREADS
#ifdef WITH_THREAD
    PyThread_acquire_lock(_PyOS_ReadlineLock, 1);
#endif

    /* This is needed to handle the unlikely case that the
     * interpreter is in interactive mode *and* stdin/out are not
     * a tty.  This can happen, for example if python is run like
     * this: python -i < test1.py
     */
    if (!isatty (fileno (sys_stdin)) || !isatty (fileno (sys_stdout)))
        rv = PyOS_StdioReadline (sys_stdin, sys_stdout, prompt);
    else
        rv = (*PyOS_ReadlineFunctionPointer)(sys_stdin, sys_stdout,
                                             prompt);
    Py_END_ALLOW_THREADS

#ifdef WITH_THREAD
    PyThread_release_lock(_PyOS_ReadlineLock);
#endif

    _PyOS_ReadlineTState = NULL;

    if (rv == NULL)
        return NULL;

    len = strlen(rv) + 1;
    res = PyMem_Malloc(len);
    if (res != NULL)
        memcpy(res, rv, len);
    PyMem_RawFree(rv);

    return res;
}