On 2015-05-27 15.33, Paul Tan wrote:
> A common usage pattern of open() is to check if it was successful, and
> die() if it was not:
>
> int fd = open(path, O_WRONLY | O_CREAT, 0777);
> if (fd < 0)
> die_errno(_("Could not open '%s' for writing."), path);
>
> Implement a wrapper function xopen() that does the above so that we can
> save a few lines of code, and make the die() messages consistent.
>
> Signed-off-by: Paul Tan <pyoka...@gmail.com>
> ---
> git-compat-util.h | 1 +
> wrapper.c | 18 ++++++++++++++++++
> 2 files changed, 19 insertions(+)
>
> diff --git a/git-compat-util.h b/git-compat-util.h
> index 17584ad..9745962 100644
> --- a/git-compat-util.h
> +++ b/git-compat-util.h
> @@ -718,6 +718,7 @@ extern char *xstrndup(const char *str, size_t len);
> extern void *xrealloc(void *ptr, size_t size);
> extern void *xcalloc(size_t nmemb, size_t size);
> extern void *xmmap(void *start, size_t length, int prot, int flags, int fd,
> off_t offset);
> +extern int xopen(const char *path, int flags, mode_t mode);
> extern ssize_t xread(int fd, void *buf, size_t len);
> extern ssize_t xwrite(int fd, const void *buf, size_t len);
> extern ssize_t xpread(int fd, void *buf, size_t len, off_t offset);
> diff --git a/wrapper.c b/wrapper.c
> index c1a663f..971665a 100644
> --- a/wrapper.c
> +++ b/wrapper.c
> @@ -189,6 +189,24 @@ void *xcalloc(size_t nmemb, size_t size)
> # endif
> #endif
>
The original open can take 2 or 3 parameters, how about this:
int xopen(const char *path, int oflag, ... )
{
va_list params;
int mode;
int fd;
va_start(params, oflag);
mode = va_arg(params, int);
va_end(params);
fd = open(path, oflag, mode);
> +/**
> + * xopen() is the same as open(), but it die()s if the open() fails.
> + */
> +int xopen(const char *path, int flags, mode_t mode)
> +{
> + int fd;
> +
> + assert(path);
> + fd = open(path, flags, mode);
> + if (fd < 0) {
> + if ((flags & O_WRONLY) || (flags & O_RDWR))
> + die_errno(_("could not open '%s' for writing"), path);
This is only partly true:
it could be either "writing" or "read write".
I don't know if the info "for reading" or "for writing" is needed/helpful at
all,
or if a simple "could not open" would be enough.
Another thing:
should we handle EINTR ?
(Somewhere in the back of my head I remember that some OS
returned EINTR when handling some foreign file system
Mac OS / NTFS ?)
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