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sprompt.c
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1 /*-------------------------------------------------------------------------
2  *
3  * sprompt.c
4  * simple_prompt() routine
5  *
6  * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
7  * Portions Copyright (c) 1994, Regents of the University of California
8  *
9  *
10  * IDENTIFICATION
11  * src/common/sprompt.c
12  *
13  *-------------------------------------------------------------------------
14  */
15 #include "c.h"
16 
17 #include "common/fe_memutils.h"
18 #include "common/string.h"
19 
20 #ifdef HAVE_TERMIOS_H
21 #include <termios.h>
22 #endif
23 
24 
25 /*
26  * simple_prompt
27  *
28  * Generalized function especially intended for reading in usernames and
29  * passwords interactively. Reads from /dev/tty or stdin/stderr.
30  *
31  * prompt: The prompt to print, or NULL if none (automatically localized)
32  * echo: Set to false if you want to hide what is entered (for passwords)
33  *
34  * The input (without trailing newline) is returned as a malloc'd string.
35  * Caller is responsible for freeing it when done.
36  */
37 char *
38 simple_prompt(const char *prompt, bool echo)
39 {
40  return simple_prompt_extended(prompt, echo, NULL);
41 }
42 
43 /*
44  * simple_prompt_extended
45  *
46  * This is the same as simple_prompt(), except that prompt_ctx can
47  * optionally be provided to allow this function to be canceled via an
48  * existing SIGINT signal handler that will longjmp to the specified place
49  * only when *(prompt_ctx->enabled) is true. If canceled, this function
50  * returns an empty string, and prompt_ctx->canceled is set to true.
51  */
52 char *
53 simple_prompt_extended(const char *prompt, bool echo,
54  PromptInterruptContext *prompt_ctx)
55 {
56  char *result;
57  FILE *termin,
58  *termout;
59 #if defined(HAVE_TERMIOS_H)
60  struct termios t_orig,
61  t;
62 #elif defined(WIN32)
63  HANDLE t = NULL;
64  DWORD t_orig = 0;
65 #endif
66 
67 #ifdef WIN32
68 
69  /*
70  * A Windows console has an "input code page" and an "output code page";
71  * these usually match each other, but they rarely match the "Windows ANSI
72  * code page" defined at system boot and expected of "char *" arguments to
73  * Windows API functions. The Microsoft CRT write() implementation
74  * automatically converts text between these code pages when writing to a
75  * console. To identify such file descriptors, it calls GetConsoleMode()
76  * on the underlying HANDLE, which in turn requires GENERIC_READ access on
77  * the HANDLE. Opening termout in mode "w+" allows that detection to
78  * succeed. Otherwise, write() would not recognize the descriptor as a
79  * console, and non-ASCII characters would display incorrectly.
80  *
81  * XXX fgets() still receives text in the console's input code page. This
82  * makes non-ASCII credentials unportable.
83  *
84  * Unintuitively, we also open termin in mode "w+", even though we only
85  * read it; that's needed for SetConsoleMode() to succeed.
86  */
87  termin = fopen("CONIN$", "w+");
88  termout = fopen("CONOUT$", "w+");
89 #else
90 
91  /*
92  * Do not try to collapse these into one "w+" mode file. Doesn't work on
93  * some platforms (eg, HPUX 10.20).
94  */
95  termin = fopen("/dev/tty", "r");
96  termout = fopen("/dev/tty", "w");
97 #endif
98  if (!termin || !termout
99 #ifdef WIN32
100 
101  /*
102  * Direct console I/O does not work from the MSYS 1.0.10 console. Writes
103  * reach nowhere user-visible; reads block indefinitely. XXX This affects
104  * most Windows terminal environments, including rxvt, mintty, Cygwin
105  * xterm, Cygwin sshd, and PowerShell ISE. Switch to a more-generic test.
106  */
107  || (getenv("OSTYPE") && strcmp(getenv("OSTYPE"), "msys") == 0)
108 #endif
109  )
110  {
111  if (termin)
112  fclose(termin);
113  if (termout)
114  fclose(termout);
115  termin = stdin;
116  termout = stderr;
117  }
118 
119  if (!echo)
120  {
121 #if defined(HAVE_TERMIOS_H)
122  /* disable echo via tcgetattr/tcsetattr */
123  tcgetattr(fileno(termin), &t);
124  t_orig = t;
125  t.c_lflag &= ~ECHO;
126  tcsetattr(fileno(termin), TCSAFLUSH, &t);
127 #elif defined(WIN32)
128  /* need the file's HANDLE to turn echo off */
129  t = (HANDLE) _get_osfhandle(_fileno(termin));
130 
131  /* save the old configuration first */
132  GetConsoleMode(t, &t_orig);
133 
134  /* set to the new mode */
135  SetConsoleMode(t, ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT);
136 #endif
137  }
138 
139  if (prompt)
140  {
141  fputs(_(prompt), termout);
142  fflush(termout);
143  }
144 
145  result = pg_get_line(termin, prompt_ctx);
146 
147  /* If we failed to read anything, just return an empty string */
148  if (result == NULL)
149  result = pg_strdup("");
150 
151  /* strip trailing newline, including \r in case we're on Windows */
152  (void) pg_strip_crlf(result);
153 
154  if (!echo)
155  {
156  /* restore previous echo behavior, then echo \n */
157 #if defined(HAVE_TERMIOS_H)
158  tcsetattr(fileno(termin), TCSAFLUSH, &t_orig);
159  fputs("\n", termout);
160  fflush(termout);
161 #elif defined(WIN32)
162  SetConsoleMode(t, t_orig);
163  fputs("\n", termout);
164  fflush(termout);
165 #endif
166  }
167  else if (prompt_ctx && prompt_ctx->canceled)
168  {
169  /* also echo \n if prompt was canceled */
170  fputs("\n", termout);
171  fflush(termout);
172  }
173 
174  if (termin != stdin)
175  {
176  fclose(termin);
177  fclose(termout);
178  }
179 
180  return result;
181 }
#define _(x)
Definition: elog.c:89
char * pg_strdup(const char *in)
Definition: fe_memutils.c:85
static void const char fflush(stdout)
char * pg_get_line(FILE *stream, PromptInterruptContext *prompt_ctx)
Definition: pg_get_line.c:59
char * simple_prompt_extended(const char *prompt, bool echo, PromptInterruptContext *prompt_ctx)
Definition: sprompt.c:53
char * simple_prompt(const char *prompt, bool echo)
Definition: sprompt.c:38
int pg_strip_crlf(char *str)
Definition: string.c:121