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FGETS(3) BSD Library Functions Manual FGETS(3) NAME fgets, gets, gets_s -- 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_s(char *str, rsize_t size); 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_s() function is equivalent to fgets() with a stream of stdin, except that the newline character (if any) is not stored in 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 in- put line, if any, is sufficiently short to fit in the string. RETURN VALUES Upon successful completion, fgets(), gets_s(), 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(), gets_s(), and gets() functions do not distinguish between end-of-file and error, and callers must use feof(3) and ferror(3) to de- termine 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() and gets_s() may also fail and set errno for any of the errors specified for the routine getchar(3). 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"). gets_s() conforms to ISO/IEC 9899:2011 ("ISO C11") K.3.7.4.1. gets() has been removed from ISO/IEC 9899:2011 ("ISO C11"). 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. BSD April 3, 2018 BSD
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | STANDARDS | SECURITY CONSIDERATIONS
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