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Add optional buffer-size to file/open. 

This calls setvbuf to change FILE buffering. A goal is
to be able to use the existing file/* functions for blocking
IO analogous to `read` and `write` system calls.
This commit is contained in:
Calvin Rose 2023-09-23 08:52:54 -05:00
parent c31314be38
commit e00a461c26
1 changed files with 11 additions and 2 deletions
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13
src/core/io.c
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@ -131,7 +131,7 @@ JANET_CORE_FN(cfun_io_temp,
}
JANET_CORE_FN(cfun_io_fopen,
"(file/open path &opt mode)",
"(file/open path &opt mode buffer-size)",
"Open a file. `path` is an absolute or relative path, and "
"`mode` is a set of flags indicating the mode to open the file in. "
"`mode` is a keyword where each character represents a flag. If the file "
@ -145,7 +145,7 @@ JANET_CORE_FN(cfun_io_fopen,
"* + - append to the file instead of overwriting it\n\n"
"* n - error if the file cannot be opened instead of returning nil\n\n"
"See fopen (<stdio.h>, C99) for further details.") {
janet_arity(argc, 1, 2);
janet_arity(argc, 1, 3);
const uint8_t *fname = janet_getstring(argv, 0);
const uint8_t *fmode;
int32_t flags;
@ -158,6 +158,15 @@ JANET_CORE_FN(cfun_io_fopen,
flags = JANET_FILE_READ;
}
FILE *f = fopen((const char *)fname, (const char *)fmode);
if (f != NULL) {
size_t bufsize = janet_optsize(argv, argc, 2, BUFSIZ);
if (bufsize != BUFSIZ) {
int result = setvbuf(f, NULL, bufsize ? _IOFBF : _IONBF, bufsize);
if (result) {
janet_panic("failed to set buffer size for file");
}
}
}
return f ? janet_makefile(f, flags)
: (flags & JANET_FILE_NONIL) ? (janet_panicf("failed to open file %s: %s", fname, strerror(errno)), janet_wrap_nil())
: janet_wrap_nil();