Messages in this thread | | | Date | Tue, 16 Jan 2018 12:19:13 -0500 | From | Steven Rostedt <> | Subject | Re: [PATCH v3 1/3] trace-cmd: Make read_proc() to return int status via OUT arg |
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On Tue, 16 Jan 2018 09:47:42 +0200 "Vladislav Valtchev (VMware)" <vladislav.valtchev@gmail.com> wrote:
> + errno = 0; > + > + /* Read an integer from buf ignoring any non-digit trailing characters. */ > + num = strtol(buf, NULL, 10); > + > + /* strtol() returned 0: we have to check for errors */ > + if (!num && (errno == EINVAL || errno == ERANGE)) > + return -1;
Repeating again here. According to the man page of strtol():
RETURN VALUE The strtol() function returns the result of the conversion, unless the value would underflow or overflow. If an underflow occurs, strtol() returns LONG_MIN. If an overflow occurs, strtol() returns LONG_MAX. In both cases, errno is set to ERANGE. Precisely the same holds for strtoll() (with LLONG_MIN and LLONG_MAX instead of LONG_MIN and LONG_MAX).
and this:
The implementation may also set errno to EINVAL in case no conversion was performed (no digits seen, and 0 returned).
Thus, !num is not enough. The example in the man page has:
errno = 0; /* To distinguish success/failure after call */ val = strtol(str, &endptr, base);
/* Check for various possible errors */
if ((errno == ERANGE && (val == LONG_MAX || val == LONG_MIN)) || (errno != 0 && val == 0)) { perror("strtol"); exit(EXIT_FAILURE); }
Let's follow this.
-- Steve
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