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libc Reference

This page documents the current BoredOS userland libc surface from external/libc/include/.

BoredOS libc is a compact implementation focused on the APIs used by in-tree apps. It is not a full glibc replacement.

Header Overview

Header Focus
stdlib.h allocation, conversion, process helpers
string.h memory/string primitives
stdio.h FILE* and formatted I/O
unistd.h POSIX-like fd/process calls
fcntl.h open/fcntl flags, dup, pipe
poll.h event-driven I/O multiplexing
signal.h signal handlers and masks
sys/stat.h stat/fstat and file mode bits
sys/types.h core typedefs (pid_t, ssize_t, ...)
sys/wait.h waitpid and wait macros
sys/ioctl.h device-specific I/O control operations
sys/kd.h console display mode definitions
errno.h errno values
time.h time/date utilities
math.h floating-point math helpers

stdlib.h

Implemented core functions:

  • Memory: malloc, free, calloc, realloc
  • Memory aliases: memset, memcpy
  • Conversions: atoi, itoa, strtod, abs
  • Output: puts, printf
  • Process/environment: exit, _exit, sleep, chdir, getcwd, access, system, getenv, abort

Notes:

  • sleep is millisecond-based and maps to kernel sleep command.
  • system is a stub-style helper in this libc, not a full shell launcher equivalent.

string.h

Implemented C string/memory set includes:

  • Memory: memmove, memcmp, memcpy, memset, memchr
  • Search: strchr, strrchr, strpbrk, strstr
  • Span: strspn, strcspn
  • Compare: strcmp, strncmp, strcasecmp, strncasecmp, strcoll
  • Build/copy: strlen, strcpy, strcat, strdup
  • Errors: strerror

stdio.h

Provided API includes:

  • Stream open/close: fopen, freopen, fclose
  • Read/write: fread, fwrite, fgets, fputs, getc, fputc, putchar
  • Positioning: fseek, ftell, filelength
  • Formatting: fprintf, vfprintf, snprintf, vsnprintf, sprintf, sscanf
  • Stream state: feof, ferror, clearerr, fflush, ungetc
  • Temp/filesystem helpers: remove, rename, tmpfile, tmpnam

unistd.h

Provided POSIX-like interfaces:

  • FD I/O: read, write, close, lseek, isatty
  • Filesystem: unlink
  • Exec family: execv, execve, execvp, execl, execlp, execle
  • Process wait: waitpid

Also defines:

  • SEEK_SET, SEEK_CUR, SEEK_END
  • F_OK, X_OK, W_OK, R_OK

fcntl.h

Flags and fd control:

  • Open flags: O_RDONLY, O_WRONLY, O_RDWR, O_CREAT, O_EXCL, O_TRUNC, O_APPEND, O_NONBLOCK, O_ACCMODE
  • fcntl ops: F_GETFL, F_SETFL
  • FD flag: FD_CLOEXEC (declared)

Functions:

  • open
  • fcntl
  • dup
  • dup2
  • pipe

signal.h

Current signal surface:

  • Basic handler API: signal, raise, kill
  • POSIX-style API: sigaction, sigprocmask, sigpending
  • Types: sighandler_t, sigset_t, struct sigaction
  • Constants: SIGINT, SIGTERM, SIGKILL, SIG_DFL, SIG_IGN, SIG_ERR
  • Mask ops: SIG_BLOCK, SIG_UNBLOCK, SIG_SETMASK
  • Action flags: SA_RESTART, SA_NODEFER, SA_RESETHAND

ctype.h

Character classification and case conversion:

  • isdigit, isalpha, isalnum, isspace
  • isupper, islower, isxdigit
  • iscntrl, ispunct, isprint, isgraph
  • tolower, toupper

locale.h

Locale stubs and conventions:

  • struct lconv
  • setlocale
  • localeconv
  • LC_ALL

limits.h

Integer and floating-point limit macros:

  • CHAR_BIT, INT_MIN, INT_MAX, UINT_MAX
  • LONG_MIN, LONG_MAX, ULONG_MAX
  • LLONG_MIN, LLONG_MAX, ULLONG_MAX
  • DBL_MAX

setjmp.h

Non-local jump support:

  • jmp_buf
  • setjmp
  • longjmp

time.h

Time/date APIs and types:

  • Types: time_t, clock_t, struct tm
  • Constants: CLOCKS_PER_SEC
  • Functions: time, clock, localtime, gmtime, strftime, mktime

sys/ioctl.h and sys/kd.h

sys/ioctl.h provides device-specific input/output control operations:

  • Framebuffer info queries (FBIOGET_VSCREENINFO, FBIOGET_FSCREENINFO)
  • TTY console window size queries (TIOCGWINSZ)
  • Console keyboard display mode settings (KDSETMODE)

sys/kd.h provides console display constants:

  • KDSETMODE ioctl command (0x4B3A)
  • KD_TEXT standard console mode (0x00) to restore text blitting
  • KD_GRAPHICS graphics mode (0x01) to stop TTY text blitting for raw /dev/fb0 access

sys/stat.h and sys/types.h

sys/stat.h provides:

  • struct stat
  • stat, fstat, mkdir
  • mode/type macros (S_IFREG, S_IFDIR, S_ISREG, S_ISDIR, permission bits)

Note:

  • access is declared in stdlib.h in this libc.

sys/types.h provides:

  • ssize_t, off_t, mode_t, pid_t, uid_t, gid_t

sys/wait.h

  • waitpid
  • WNOHANG
  • status macros: WEXITSTATUS, WIFEXITED, WTERMSIG, WIFSIGNALED

errno.h

Defined errno values include:

  • Generic/input: EINVAL, EDOM, ERANGE, E2BIG
  • File/path: ENOENT, EEXIST, EISDIR, ENOTDIR, EBADF
  • Runtime/state: ENOMEM, EACCES, EIO, EAGAIN, EINTR, ECHILD, EBUSY, EPIPE, ESPIPE, ENOSYS, ENOTSUP

Relationship to raw syscalls

  • libc high-level I/O and process APIs are backed by wrappers in external/libc/src/syscall.c.
  • Full syscall command IDs and multiplexer details are documented in docs/appdev/syscalls.md.

Practical Guidance

  • Prefer libc APIs (open, read, write, waitpid, sigaction) for portability inside BoredOS userland.
  • Use raw wrapper calls from syscall.h only for capabilities that do not yet have higher-level libc wrappers.
  • Avoid numeric sys_system(...) command literals in app code; use SYSTEM_CMD_* macros.