vlibc/include/stdio.h

#ifndef VLIBC_STDIO_H
#define VLIBC_STDIO_H

/*
 * vlibc — <stdio.h>.
 *
 * Buffered stream I/O (todo 15). The FILE object is opaque to consumers;
 * the layout lives in src/stdio/stdio_impl.h. stdin/stdout/stderr are
 * pre-wired streams over fds 0/1/2 and are initialized lazily on first
 * use. On Linux there is no text/binary distinction, so the 'b' mode
 * character is accepted and ignored.
 *
 * Buffering modes for setvbuf: _IOFBF (fully buffered), _IOLBF (line
 * buffered: flush on newline), _IONBF (unbuffered). A stream opened on a
 * terminal defaults to line buffering for stdout and full buffering for
 * stdin; stderr is always unbuffered.
 *
 * getc/putc/getchar/putchar are declared as functions (address-taking and
 * #undef work) and additionally defined as macros over fgetc/fputc; the
 * macro arguments are evaluated exactly once.
 *
 * Level 2 (muslmimic) adds tmpnam/ctermid/setbuffer/setlinebuf and the
 * fopen64 name alias (identical ABI on LP64).
 */

#include <vlibc/features.h>

#include <stdarg.h>
#include <stddef.h>
#include <sys/types.h>

#ifdef __cplusplus
extern "C" {
#endif

/*
 * The opaque stream object. The underlying struct tag is vlibc_FILE (see
 * src/stdio/stdio_impl.h); consumers only ever use FILE *.
 */
typedef struct vlibc_FILE FILE;

/* The three pre-wired standard streams (fds 0, 1, 2). */
extern FILE *stdin;
extern FILE *stdout;
extern FILE *stderr;

/* End of file indicator for character functions. */
#define EOF (-1)

/* Minimum number of simultaneously open files. */
#define FOPEN_MAX 16

/* Default buffer size for setvbuf/setbuf. */
#define BUFSIZ 8192

/* Maximum length of a path argument for stdio functions. */
#define FILENAME_MAX 4096

/* Minimum number of distinct tmpnam-generated names. */
#define TMP_MAX 238328

/* Buffer sizes for tmpnam and ctermid results. */
#define L_tmpnam 20
#define L_ctermid 9

/* Seek positions for fseek/fseeko. */
#define SEEK_SET 0
#define SEEK_CUR 1
#define SEEK_END 2

/* setvbuf modes. */
#define _IOFBF 0 // NOLINT(bugprone-reserved-identifier)
#define _IOLBF 1 // NOLINT(bugprone-reserved-identifier)
#define _IONBF 2 // NOLINT(bugprone-reserved-identifier)

/* Opaque file position type for fgetpos/fsetpos. */
typedef off_t fpos_t;

/*
 * Open the file at path with the given mode. The mode is 'r', 'w', or 'a',
 * optionally followed by '+' (update: read and write), 'b' (ignored on
 * Linux), and/or 'x' (exclusive create, C11). Returns NULL with errno set
 * on failure.
 */
FILE *
fopen(const char *restrict path, const char *restrict mode);

/*
 * Wrap an existing descriptor in a stream. The requested mode must be
 * compatible with the descriptor's access mode (basic check via fcntl).
 * The descriptor is not duplicated; fclose closes it.
 */
FILE *
fdopen(int fd, const char *mode);

/*
 * Rebind stream to path. The old descriptor is flushed and closed first.
 * With path == NULL only the mode changes and the descriptor stays open.
 * Returns NULL with errno set on failure.
 */
FILE *
freopen(const char *restrict path, const char *restrict mode, FILE *restrict stream);

/*
 * Flush pending output, close the descriptor, and release the stream.
 * Returns EOF if flushing or closing failed.
 */
int
fclose(FILE *stream);

/*
 * Flush pending output of stream. fflush(NULL) flushes all open streams
 * with pending output. On a stream with no pending writes (read mode) the
 * unread buffered data is discarded and the position rewound; this never
 * corrupts the stream. Returns EOF on error.
 */
int
fflush(FILE *stream);

/*
 * Set the buffer of stream to buf. buf == NULL selects unbuffered I/O;
 * otherwise the buffer is used with full buffering and BUFSIZ size. Must
 * be called before the first operation on the stream.
 */
void
setbuf(FILE *restrict stream, char *restrict buf);

/*
 * Set the buffering mode of stream: _IOFBF, _IOLBF, or _IONBF. With
 * buf != NULL the caller supplies size bytes of storage; with buf == NULL
 * the buffer is allocated lazily on first use (size is then ignored,
 * except that _IONBF needs no buffer). Returns 0, or -1 with errno EINVAL
 * for an invalid mode or a non-NULL buf with size 0 (except _IONBF).
 */
int
setvbuf(FILE *restrict stream, char *restrict buf, int mode, size_t size);

/*
 * Read up to size * nmemb bytes in items of size bytes each. Returns the
 * number of complete items read; fewer than nmemb means end of file or an
 * error (distinguishable via feof/ferror). size or nmemb zero returns 0
 * without touching the stream.
 */
size_t
fread(void *restrict ptr, size_t size, size_t nmemb, FILE *restrict stream);

/*
 * Write size * nmemb bytes in items of size bytes each. Returns the number
 * of complete items written; fewer than nmemb means an error (see
 * ferror).
 */
size_t
fwrite(const void *restrict ptr, size_t size, size_t nmemb, FILE *restrict stream);

/* Read the next character as unsigned char, or EOF. */
int
fgetc(FILE *stream);

/* Write c as unsigned char; returns it, or EOF on error. */
int
fputc(int c, FILE *stream);

/* Same as fgetc/fputc; also provided as macros (arguments evaluated once). */
int
getc(FILE *stream);

int
putc(int c, FILE *stream);

int
getchar(void);

int
putchar(int c);

/*
 * Read at most n-1 characters into s, stopping after (and keeping) a
 * newline, then NUL-terminate. Returns s, or NULL if no character was read
 * (end of file or error).
 */
char *
fgets(char *restrict s, int n, FILE *restrict stream);

/*
 * Write the NUL-terminated string s to stream (no trailing newline is
 * added). Returns a non-negative value, or EOF on error.
 */
int
fputs(const char *restrict s, FILE *restrict stream);

/*
 * Push c back onto the input stream; the next read returns it again. One
 * byte of pushback is guaranteed. Returns c, or EOF on error (also for
 * ungetc(EOF)). A successful seek discards the pushed-back character.
 */
int
ungetc(int c, FILE *stream);

/* Position the stream (see SEEK_SET/SEEK_CUR/SEEK_END); clears feof. */
int
fseek(FILE *stream, long offset, int whence);

int
fseeko(FILE *stream, off_t offset, int whence);

/* Current stream position, -1 with errno set on error. */
long
ftell(FILE *stream);

/*
 * Not marked pure: the implementation can allocate the stream buffer on
 * first use (an observable side effect), so the compiler must not elide
 * or reorder the call. (feof/ferror/fileno below are genuinely read-only
 * and keep their pure attribute.)
 */
off_t
ftello(FILE *stream);

/* Rewind to the start and clear feof/ferror (equivalent to
 * fseeko(stream, 0, SEEK_SET) + clearerr). */
void
rewind(FILE *stream);

/* Get/set the opaque position via fpos_t. */
int
fgetpos(FILE *restrict stream, fpos_t *restrict pos);

int
fsetpos(FILE *stream, const fpos_t *pos);

/* End-of-file and error indicators. */
__attribute__((pure)) int
feof(FILE *stream);

__attribute__((pure)) int
ferror(FILE *stream);

void
clearerr(FILE *stream);

/*
 * Remove the file at path (a directory is removed like rmdir). Returns 0,
 * or -1 with errno set.
 */
int
remove(const char *path);

/* Rename oldpath to newpath. Returns 0, or -1 with errno set. */
int
rename(const char *oldpath, const char *newpath);

/*
 * Create an anonymous temporary file ("w+b"): the file is created in /tmp
 * and unlinked immediately, so it disappears on close. Returns the stream,
 * or NULL with errno set.
 */
FILE *
tmpfile(void);

/* The descriptor underlying the stream. */
__attribute__((pure)) int
fileno(FILE *stream);

/*
 * Run command in a subshell ("sh -c command") with a pipe attached to
 * its standard output (mode "r") or standard input (mode "w"). Only the
 * two POSIX modes are accepted (the glibc "re"/"we" close-on-exec
 * extension is not). Returns the stream, or NULL with errno set.
 * pclose closes the stream, waits for the shell, and returns its
 * termination status (the raw wait status, e.g. 0 for "exit 0"), or -1
 * when the stream was not opened by popen or the wait failed.
 */
FILE *
popen(const char *command, const char *mode);

int
pclose(FILE *stream);

/* getc/putc/getchar/putchar as macros over fgetc/fputc (see above). */
#define getc(stream) fgetc(stream)
#define putc(c, stream) fputc((c), (stream))
#define getchar() fgetc(stdin)
#define putchar(c) fputc((c), stdout)

#if VLIBC_LEVEL_GE(2)

/*
 * Generate a name for a temporary file ("/tmp/vlibcXXXXXX" form; the file
 * is NOT created). With s == NULL a static buffer is used. Not thread-safe,
 * obsolescent.
 */
char *
tmpnam(char *s);

/* Controlling terminal path: copies "/dev/tty" into s (or a static
 * buffer when s == NULL) and returns it. */
char *
ctermid(char *s);

/* BSD: like setvbuf with _IOFBF/_IONBF and the given size. */
void
setbuffer(FILE *stream, char *buf, size_t size);

/* BSD: select line buffering (setvbuf with _IOLBF and NULL buffer). */
void
setlinebuf(FILE *stream);

/* glibc LFS name alias: identical to fopen on LP64. */
FILE *
fopen64(const char *restrict path, const char *restrict mode);

#endif /* VLIBC_LEVEL_GE(2) */

#ifdef __cplusplus
}
#endif

/* formatted output (todo 16) */

int
printf(const char *restrict format, ...);
int
fprintf(FILE *restrict stream, const char *restrict format, ...);
int
sprintf(char *restrict s, const char *restrict format, ...);
int
snprintf(char *restrict s, size_t n, const char *restrict format, ...);
int
vprintf(const char *restrict format, va_list ap);
int
vfprintf(FILE *restrict stream, const char *restrict format, va_list ap);
int
vsprintf(char *restrict s, const char *restrict format, va_list ap);
int
vsnprintf(char *restrict s, size_t n, const char *restrict format, va_list ap);
int
dprintf(int fd, const char *restrict format, ...);
int
vdprintf(int fd, const char *restrict format, va_list ap);
void
perror(const char *s);

#if VLIBC_LEVEL_GE(2)
int
asprintf(char **restrict strp, const char *restrict format, ...);
int
vasprintf(char **restrict strp, const char *restrict format, va_list ap);
#endif

/* line input, stream locking, and memory streams (todo 18) */

/*
 * Read one line from stream into a malloc'd, NUL-terminated buffer. On the
 * first call *lineptr may be NULL (a buffer is allocated); *n is the buffer
 * capacity and grows as needed. The newline is kept in the output; embedded
 * NUL bytes are preserved (the length comes from the return value, not
 * strlen). Returns the number of bytes read including the delimiter, or -1
 * at end of file (nothing read) or on error.
 */
ssize_t
getline(char **restrict lineptr, size_t *restrict n, FILE *restrict stream);

/*
 * Like getline, but reads up to the given delimiter byte (which is kept in
 * the output). Reading stops at end of file without the delimiter; a partial
 * final line is still returned with its byte count.
 */
ssize_t
getdelim(char **restrict lineptr, size_t *restrict n, int delim, FILE *restrict stream);

/* Write s to stdout followed by a newline. Returns a non-negative value,
 * or EOF on error. */
int
puts(const char *s);

/*
 * Per-stream advisory locks (POSIX.1-2008 base). flockfile is recursive:
 * the owning thread may lock the same stream any number of times, and
 * funlockfile must be called once per successful flockfile. ftrylockfile
 * acquires without blocking: 0 on success, nonzero when the stream is
 * already locked. Single-threaded today; the lock fields become real
 * blocking locks when the thread runtime lands.
 */
void
flockfile(FILE *stream);

int
ftrylockfile(FILE *stream);

void
funlockfile(FILE *stream);

/*
 * Unlocked character I/O: the stream must already be locked by the caller
 * (see flockfile). Identical to fgetc/fputc over stdin/stdout without
 * taking the per-stream lock.
 */
int
getc_unlocked(FILE *stream);

int
getchar_unlocked(void);

int
putc_unlocked(int c, FILE *stream);

int
putchar_unlocked(int c);

/*
 * Open a stream over the memory region buf of size bytes. With buf == NULL
 * the stream allocates and owns a growable buffer of its own that is freed
 * on fclose. Modes are fopen-like ('r', 'w', 'a', optional '+' and 'b',
 * where 'b' is accepted but on Linux only disables the string semantics):
 * 'w' truncates the current length to zero, 'a' positions at the end of the
 * data currently in the buffer (the first NUL byte in string mode), and
 * writing past the buffer size is an error. Returns the stream, or NULL
 * with errno set.
 */
FILE *
fmemopen(void *buf, size_t size, const char *mode);

/*
 * Open a write-only dynamic memory stream. The stream owns a growable
 * buffer; after fflush or fclose the buffer is NUL-terminated at the current
 * data length, *ptr points at it (it may have moved), and *sizeloc holds the
 * length. The caller releases the buffer with free() after fclose.
 */
FILE *
open_memstream(char **ptr, size_t *sizeloc);

#endif /* VLIBC_STDIO_H */