fgets(3) BSD Library Functions Manual fgets(3)
NAME
fgets, gets -- get a line from a stream
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <stdio.h>
char *
fgets(char * restrict str, int size, FILE * restrict stream);
char *
gets(char *str);
DESCRIPTION
The fgets() function reads at most one less than the number of characters
specified by size from the given stream and stores them in the string
str. Reading stops when a newline character is found, at end-of-file or
error. The newline, if any, is retained. If any characters are read and
there is no error, a `\0' character is appended to end the string.
The gets() function is equivalent to fgets() with an infinite size and a
stream of stdin, except that the newline character (if any) is not stored
in the string. It is the caller's responsibility to ensure that the
input line, if any, is sufficiently short to fit in the string.
RETURN VALUES
Upon successful completion, fgets() and gets() return a pointer to the
string. If end-of-file occurs before any characters are read, they
return NULL and the buffer contents remain unchanged. If an error
occurs, they return NULL and the buffer contents are indeterminate. The
fgets() and gets() functions do not distinguish between end-of-file and
error, and callers must use feof(3) and ferror(3) to determine which
occurred.
ERRORS
[EBADF] The given stream is not a readable stream.
The function fgets() may also fail and set errno for any of the errors
specified for the routines fflush(3), fstat(2), read(2), or malloc(3).
The function gets() may also fail and set errno for any of the errors
specified for the routine getchar(3).
SECURITY CONSIDERATIONS
The gets() function cannot be used securely. Because of its lack of
bounds checking, and the inability for the calling program to reliably
determine the length of the next incoming line, the use of this function
enables malicious users to arbitrarily change a running program's func-
tionality through a buffer overflow attack. It is strongly suggested
that the fgets() function be used in all cases. (See the FSA.)
SEE ALSO
feof(3), ferror(3), fgetln(3), fgetws(3), getline(3)
STANDARDS
The functions fgets() and gets() conform to ISO/IEC 9899:1999
(``ISO C99'').
BSD June 4, 1993 BSD
Mac OS X 10.8 - Generated Mon Aug 27 18:14:25 CDT 2012