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https://git.proxmox.com/git/wasi-libc
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a6f8713433
* Convert preopen initialization to be lazy. Insteead of eagerly initializing the preopens in a static constructor, perform preopen initialization the first time it's needed, or before a close or a renumber which might disrupt the file descriptor space. And, use a weak symbol with a stub function for use by `close` or `fd_renumber`, we that they can trigger preopen initialization only if it's actually needed. This way, if a program doesn't contain any calls to any function that needs preopens, it can avoid linking in the preopen initialization code. And if it contains calls but doesn't execute them at runtime, it can avoid executing the preopen intiailization code. A downside here is that this may cause problems for users that call `__wasi_fd_close` or `__wasi_fd_renumber` directly and close over overwrite some preopens before libc has a chance to scan them. To partially address this, this PR does add a declaration for `__wasilibc_populate_preopens` to <wasi/libc.h> so that users can call it manually if they need to. * Fix calling `internal_register_preopened_fd` with the lock held. Factor out the lock acquisition from the implementation of `internal_register_preopened_fd` so that we can call it from `__wasilibc_populate_preopens` with the lock held.
72 lines
2.7 KiB
C
72 lines
2.7 KiB
C
#ifndef __wasi_libc_h
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#define __wasi_libc_h
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#include <__typedef_off_t.h>
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#include <__struct_timespec.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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struct stat;
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struct timespec;
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/// Populate libc's preopen tables. This is normally done automatically
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/// just before it's needed, however if you call `__wasi_fd_renumber` or
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/// `__wasi_fd_close` directly, and you need the preopens to be accurate
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/// afterward, you should call this before doing so.
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void __wasilibc_populate_preopens(void);
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/// Register the given pre-opened file descriptor under the given path.
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///
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/// This function does not take ownership of `prefix` (it makes its own copy).
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int __wasilibc_register_preopened_fd(int fd, const char *prefix);
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/// Renumber `fd` to `newfd`; similar to `dup2` but does a move rather than a
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/// copy.
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int __wasilibc_fd_renumber(int fd, int newfd)
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__attribute__((__warn_unused_result__));
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/// Like `unlinkat`, but without depending on `__wasi_path_remove_directory`.
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int __wasilibc_unlinkat(int fd, const char *path)
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__attribute__((__warn_unused_result__));
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/// An `*at` version of rmdir.
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int __wasilibc_rmdirat(int fd, const char *path)
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__attribute__((__warn_unused_result__));
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/// Like `open`, but without the varargs in the signature.
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int __wasilibc_open_nomode(const char *path, int oflag);
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/// Like `openat`, but without the varargs in the signature.
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int __wasilibc_openat_nomode(int fd, const char *path, int oflag);
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/// Return the current file offset. Like `lseek(fd, 0, SEEK_CUR)`, but without
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/// depending on `lseek`.
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off_t __wasilibc_tell(int fd)
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__attribute__((__warn_unused_result__));
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/* Non-`at` forms of various `*at` functions. */
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int __wasilibc_access(const char *pathname, int mode, int flags)
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__attribute__((__warn_unused_result__));
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int __wasilibc_stat(const char *__restrict pathname, struct stat *__restrict statbuf, int flags)
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__attribute__((__warn_unused_result__));
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int __wasilibc_utimens(const char *pathname, const struct timespec times[2], int flags)
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__attribute__((__warn_unused_result__));
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int __wasilibc_link(const char *oldpath, const char *newpath, int flags)
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__attribute__((__warn_unused_result__));
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int __wasilibc_link_oldat(int olddirfd, const char *oldpath, const char *newpath, int flags)
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__attribute__((__warn_unused_result__));
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int __wasilibc_link_newat(const char *oldpath, int newdirfd, const char *newpath, int flags)
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__attribute__((__warn_unused_result__));
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int __wasilibc_rename_oldat(int olddirfd, const char *oldpath, const char *newpath)
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__attribute__((__warn_unused_result__));
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int __wasilibc_rename_newat(const char *oldpath, int newdirfd, const char *newpath)
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__attribute__((__warn_unused_result__));
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#ifdef __cplusplus
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}
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#endif
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#endif
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