|
This document is a Mac OS X manual page. Manual pages are a command-line technology for providing documentation. You can view these manual pages locally using the man(1) command. These manual pages come from many different sources, and thus, have a variety of writing styles. For more information about the manual page format, see the manual page for manpages(5). |
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 s, int n, FILE *restrict stream); char * gets(char *s); DESCRIPTION The fgets() function reads at most one less than the number of characters specified by n from the given stream and stores them in the string s. 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 n 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; 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 functionality 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) STANDARDS The functions fgets() and gets() conform to ISO/IEC 9899:1999 (``ISO C99''). BSD June 4, 1993 BSD |