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Add extern int code_of_unix_error (value error); #4812

vicuna opened this issue Jun 3, 2009 · 1 comment

Add extern int code_of_unix_error (value error); #4812

vicuna opened this issue Jun 3, 2009 · 1 comment


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@vicuna vicuna commented Jun 3, 2009

Original bug ID: 4812
Reporter: goswin
Status: closed (set by @damiendoligez on 2013-08-02T14:21:48Z)
Resolution: fixed
Priority: high
Severity: minor
Target version: 4.01.0+dev
Fixed in version: 4.01.0+dev
Category: ~DO NOT USE (was: OCaml general)
Monitored by: tgazagna @ygrek @glondu

Bug description

The unixsupport.h header provides functions to convert unix errno into ocamls Unix.error, which is sufficient for most applications. The attached patch adds a function for the reverse convertion.

Additional information

For libfuse bindings I need to convert Unix.error to errno numbers. The C stubs call an ocaml closure and expect usualy a string as return value or an Unix.Unix_error exception in case of an error. The stubs need to catch the exception, convert them back to unix errno numbers and return -err to libfuse. The code looks something like this:

static int readlink_stub(const char *name, char *buf, size_t size) {
int res = 0;
CAMLlocal3(ml_name, ml_res, ml_exn);

ml_name = caml_copy_string(name);
value ml_res = caml_callback2(readlink_callback, ml_name, Val_int(size));
if (Is_exception_result(ml_res)) {
ml_exn = Extract_exception(ml_res);
res = -code_of_unix_error(Field(ml_exn, 1));
} else {
strncpy(buf, String_val(ml_res), size);
return res;

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@vicuna vicuna commented Aug 2, 2013

Comment author: @damiendoligez

Patch applied (branch 4.01, rev 13968)

@vicuna vicuna closed this Aug 2, 2013
@vicuna vicuna added this to the 4.01.0 milestone Mar 14, 2019
@vicuna vicuna added the bug label Mar 20, 2019
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