char *getpass(const char *prompt);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
This function is obsolete. Do not use it. If you want to read input without
terminal echoing enabled, see the description of the ECHO flag in
- Since glibc 2.2.2:
_XOPEN_SOURCE && ! (_POSIX_C_SOURCE >= 200112L)
|| /* Glibc since 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE
- Before glibc 2.2.2:
The getpass() function opens /dev/tty (the
controlling terminal of the process), outputs the string prompt,
turns off echoing, reads one line (the "password"), restores the
terminal state and closes /dev/tty again.
The function getpass() returns a pointer to a static buffer containing
(the first PASS_MAX bytes of) the password without the trailing
newline, terminated by a null byte ('\0'). This buffer may be overwritten by a
following call. On error, the terminal state is restored, errno is set
appropriately, and NULL is returned.
The function may fail if
For an explanation of the terms used in this section, see attributes(7).
- The process does not have a controlling terminal.
Present in SUSv2, but marked LEGACY. Removed in POSIX.1-2001.
In the GNU C library implementation, if /dev/tty cannot be opened, the
prompt is written to stderr and the password is read from stdin.
There is no limit on the length of the password. Line editing is not disabled.
According to SUSv2, the value of PASS_MAX must be defined
in <limits.h> in case it is smaller than 8, and can in any case
be obtained using sysconf(_SC_PASS_MAX). However, POSIX.2 withdraws
the constants PASS_MAX and _SC_PASS_MAX, and the function
getpass(). The glibc version accepts _SC_PASS_MAX and returns
BUFSIZ (e.g., 8192).
The calling process should zero the password as soon as possible to avoid
leaving the cleartext password visible in the process's address space.
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