How to pass in psql password from program on Windows - postgresql

Question

I am currently working on PostgreSQL backup and restore functionality for my project. I have read this http://www.codeproject.com/Articles/37154/PostgreSQL-PostGis-Operations article and followed that approach to do this. It is working fine but recently I have changed the PostgreSQL authentication method to password in the pg_hba.con file. Hence it started prompting for the password whenever I execute psql.exe, pg_dump.exe, and pg_restore.exe. To provide the password through my project, I have used the "RedirectStandardInput" method. But it did not work and psql or pg_dump still prompt for the password. However "RedirectStandardOutput" and error methods are working fine.
I went through the PostgreSQL source code and found that GetConsoleMode and SetConsoleMode are used the remove the echo. I hope ( not sure ) it could be the reason, which is why I am unable to redirect the input.
PostgreSQL source code to prompt the password
simple_prompt(const char *prompt, int maxlen, bool echo)
{
int length;
char *destination;
FILE *termin,
*termout;
#ifdef HAVE_TERMIOS_H
struct termios t_orig,
t;
#else
#ifdef WIN32
HANDLE t = NULL;
LPDWORD t_orig = NULL;
#endif
#endif
destination = (char *) malloc(maxlen + 1);
if (!destination)
return NULL;
/*
* Do not try to collapse these into one "w+" mode file. Doesn't work on
* some platforms (eg, HPUX 10.20).
*/
termin = fopen(DEVTTY, "r");
termout = fopen(DEVTTY, "w");
if (!termin || !termout
#ifdef WIN32
/* See DEVTTY comment for msys */
|| (getenv("OSTYPE") && strcmp(getenv("OSTYPE"), "msys") == 0)
#endif
)
{
if (termin)
fclose(termin);
if (termout)
fclose(termout);
termin = stdin;
termout = stderr;
}
#ifdef HAVE_TERMIOS_H
if (!echo)
{
tcgetattr(fileno(termin), &t);
t_orig = t;
t.c_lflag &= ~ECHO;
tcsetattr(fileno(termin), TCSAFLUSH, &t);
}
#else
#ifdef WIN32
if (!echo)
{
/* get a new handle to turn echo off */
t_orig = (LPDWORD) malloc(sizeof(DWORD));
t = GetStdHandle(STD_INPUT_HANDLE);
/* save the old configuration first */
GetConsoleMode(t, t_orig);
/* set to the new mode */
SetConsoleMode(t, ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT);
}
#endif
#endif
if (prompt)
{
fputs(_(prompt), termout);
fflush(termout);
}
if (fgets(destination, maxlen + 1, termin) == NULL)
destination[0] = '\0';
length = strlen(destination);
if (length > 0 && destination[length - 1] != '\n')
{
/* eat rest of the line */
char buf[128];
int buflen;
do
{
if (fgets(buf, sizeof(buf), termin) == NULL)
break;
buflen = strlen(buf);
} while (buflen > 0 && buf[buflen - 1] != '\n');
}
if (length > 0 && destination[length - 1] == '\n')
/* remove trailing newline */
destination[length - 1] = '\0';
#ifdef HAVE_TERMIOS_H
if (!echo)
{
tcsetattr(fileno(termin), TCSAFLUSH, &t_orig);
fputs("\n", termout);
fflush(termout);
}
#else
#ifdef WIN32
if (!echo)
{
/* reset to the original console mode */
SetConsoleMode(t, *t_orig);
fputs("\n", termout);
fflush(termout);
free(t_orig);
}
#endif
#endif
if (termin != stdin)
{
fclose(termin);
fclose(termout);
}
return destination;
}
Please help me here, how to send the password to psql or pg_dump via C# code.

Answer 1

Since this is local to the application, the best thing to do is to set %PGPASSWORD% and then psql will not ask for the password. .pgpass could be used if you wanted to avoid supplying a password at all. In general you do not want to specify environment variables from the command line since they may show for other users but this is not a concern here.