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git/compat/terminal.c
Jeff King 67ba123fd1 terminal: seek when switching between reading and writing
When a stdio stream is opened in update mode (e.g., "w+"),
the C standard forbids switching between reading or writing
without an intervening positioning function. Many
implementations are lenient about this, but Solaris libc
will flush the recently-read contents to the output buffer.
In this instance, that meant writing the non-echoed password
that the user just typed to the terminal.

Fix it by inserting a no-op fseek between the read and
write.

The opposite direction (writing followed by reading) is also
disallowed, but our intervening fflush is an acceptable
positioning function for that alternative.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2012-08-06 22:11:47 -07:00

82 lines
1.2 KiB
C

#include "git-compat-util.h"
#include "compat/terminal.h"
#include "sigchain.h"
#include "strbuf.h"
#ifdef HAVE_DEV_TTY
static int term_fd = -1;
static struct termios old_term;
static void restore_term(void)
{
if (term_fd < 0)
return;
tcsetattr(term_fd, TCSAFLUSH, &old_term);
term_fd = -1;
}
static void restore_term_on_signal(int sig)
{
restore_term();
sigchain_pop(sig);
raise(sig);
}
char *git_terminal_prompt(const char *prompt, int echo)
{
static struct strbuf buf = STRBUF_INIT;
int r;
FILE *fh;
fh = fopen("/dev/tty", "w+");
if (!fh)
return NULL;
if (!echo) {
struct termios t;
if (tcgetattr(fileno(fh), &t) < 0) {
fclose(fh);
return NULL;
}
old_term = t;
term_fd = fileno(fh);
sigchain_push_common(restore_term_on_signal);
t.c_lflag &= ~ECHO;
if (tcsetattr(fileno(fh), TCSAFLUSH, &t) < 0) {
term_fd = -1;
fclose(fh);
return NULL;
}
}
fputs(prompt, fh);
fflush(fh);
r = strbuf_getline(&buf, fh, '\n');
if (!echo) {
fseek(fh, SEEK_CUR, 0);
putc('\n', fh);
fflush(fh);
}
restore_term();
fclose(fh);
if (r == EOF)
return NULL;
return buf.buf;
}
#else
char *git_terminal_prompt(const char *prompt, int echo)
{
return getpass(prompt);
}
#endif