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TR 24731-1 defines a new type of errno_t }} which is type {{int in <errno.h> and elsewhere. Many of the functions defined in TR 24731-1 return values of this type. As a matter of programming style, errno_t should be used as the type of something that deals only with the values that might be found in errno. For example, a function which returns the value of errno should be declared as having the return type errno_t.
Non-Compliant Code Example
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int opener(FILE* file, int *width, int *height, int *data_offset) {
int file_w;
int file_h;
int file_o;
int offset = 0;
if (file == NULL) { return -1; }
if (fscanf(file, "%i %i %i", &file_w, &file_h, &file_o) != 3) { return -1; }
if (fsetpos(file, &offset) != 0) { return -1; }
*width = file_w;
*height = file_h;
*data_offset = file_o;
return 0;
}
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Compliant Solution
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errno_t opener(FILE* file, int *width, int *height, int *data_offset) {
int file_w;
int file_h;
int file_o;
int rc;
fpos_t offset;
if (file == NULL) { return EINVAL; }
rc = fgetpos(file, &offset);
if (rc != 0) { return (errno_t)rc; }
if (fscanf(file, "%i %i %i", &file_w, &file_h, &file_o) != 3) { return EIO; }
rc = fsetpos(file, &offset);
if (rc != 0) { return -1; }
*width = file_w;
*height = file_h;
*data_offset = file_o;
return 0;
}
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| Wiki Markup |
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\[[ISO/IEC TR 24731-2006|AA. C References#ISO/IEC TR 24731-2006]\]
\[[ISO/IEC 9899-1999:TC2|AA. C References#ISO/IEC 9899-1999TC2]\] Section 6.7.5.3, "Function declarators (including prototypes)" |
