util/cutils: Rewrite documentation of qemu_strtol() & friends
Fixes the following documentation bugs:
* Fails to document that null @nptr is safe.
* Fails to document that we return -EINVAL when no conversion could be
performed (commit 47d4be1).
* Confuses long long with int64_t, and unsigned long long with
uint64_t.
* Claims the unsigned conversions can underflow. They can't.
While there, mark problematic assumptions that int64_t is long long,
and uint64_t is unsigned long long with FIXME comments.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <1487708048-2131-6-git-send-email-armbru@redhat.com>
This commit is contained in:
Markus Armbruster
parent
bc7c08a2c3
commit
4295f879be
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@ -265,9 +265,6 @@ int64_t qemu_strtosz(const char *nptr, char **end)
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static int check_strtox_error(const char *p, char *endptr, const char **next,
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int err)
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{
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/* If no conversion was performed, prefer BSD behavior over glibc
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* behavior.
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*/
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if (err == 0 && endptr == p) {
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err = EINVAL;
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}
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@ -281,30 +278,28 @@ static int check_strtox_error(const char *p, char *endptr, const char **next,
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}
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/**
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* QEMU wrappers for strtol(), strtoll(), strtoul(), strotull() C functions.
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* Convert string @nptr to a long integer, and store it in @result.
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*
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* Convert ASCII string @nptr to a long integer value
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* from the given @base. Parameters @nptr, @endptr, @base
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* follows same semantics as strtol() C function.
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* This is a wrapper around strtol() that is harder to misuse.
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* Semantics of @nptr, @endptr, @base match strtol() with differences
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* noted below.
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*
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* Unlike from strtol() function, if @endptr is not NULL, this
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* function will return -EINVAL whenever it cannot fully convert
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* the string in @nptr with given @base to a long. This function returns
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* the result of the conversion only through the @result parameter.
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* @nptr may be null, and no conversion is performed then.
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*
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* If NULL is passed in @endptr, then the whole string in @ntpr
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* is a number otherwise it returns -EINVAL.
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* If no conversion is performed, store @nptr in *@endptr and return
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* -EINVAL.
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*
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* RETURN VALUE
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* Unlike from strtol() function, this wrapper returns either
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* -EINVAL or the errno set by strtol() function (e.g -ERANGE).
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* If the conversion overflows, -ERANGE is returned, and @result
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* is set to the max value of the desired type
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* (e.g. LONG_MAX, LLONG_MAX, ULONG_MAX, ULLONG_MAX). If the case
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* of underflow, -ERANGE is returned, and @result is set to the min
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* value of the desired type. For strtol(), strtoll(), @result is set to
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* LONG_MIN, LLONG_MIN, respectively, and for strtoul(), strtoull() it
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* is set to 0.
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* If @endptr is null, and the string isn't fully converted, return
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* -EINVAL. This is the case when the pointer that would be stored in
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* a non-null @endptr points to a character other than '\0'.
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*
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* If the conversion overflows @result, store LONG_MAX in @result,
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* and return -ERANGE.
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*
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* If the conversion underflows @result, store LONG_MIN in @result,
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* and return -ERANGE.
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*
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* Else store the converted value in @result, and return zero.
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*/
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int qemu_strtol(const char *nptr, const char **endptr, int base,
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long *result)
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@ -325,17 +320,29 @@ int qemu_strtol(const char *nptr, const char **endptr, int base,
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}
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/**
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* Converts ASCII string to an unsigned long integer.
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* Convert string @nptr to an unsigned long, and store it in @result.
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*
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* If string contains a negative number, value will be converted to
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* the unsigned representation of the signed value, unless the original
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* (nonnegated) value would overflow, in this case, it will set @result
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* to ULONG_MAX, and return ERANGE.
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* This is a wrapper around strtoul() that is harder to misuse.
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* Semantics of @nptr, @endptr, @base match strtoul() with differences
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* noted below.
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*
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* The same behavior holds, for qemu_strtoull() but sets @result to
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* ULLONG_MAX instead of ULONG_MAX.
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* @nptr may be null, and no conversion is performed then.
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*
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* See qemu_strtol() documentation for more info.
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* If no conversion is performed, store @nptr in *@endptr and return
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* -EINVAL.
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*
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* If @endptr is null, and the string isn't fully converted, return
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* -EINVAL. This is the case when the pointer that would be stored in
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* a non-null @endptr points to a character other than '\0'.
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*
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* If the conversion overflows @result, store ULONG_MAX in @result,
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* and return -ERANGE.
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*
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* Else store the converted value in @result, and return zero.
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*
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* Note that a number with a leading minus sign gets converted without
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* the minus sign, checked for overflow (see above), then negated (in
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* @result's type). This is exactly how strtoul() works.
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*/
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int qemu_strtoul(const char *nptr, const char **endptr, int base,
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unsigned long *result)
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@ -360,9 +367,10 @@ int qemu_strtoul(const char *nptr, const char **endptr, int base,
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}
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/**
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* Converts ASCII string to a long long integer.
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* Convert string @nptr to an int64_t.
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*
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* See qemu_strtol() documentation for more info.
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* Works like qemu_strtol(), except it stores INT64_MAX on overflow,
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* and INT_MIN on underflow.
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*/
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int qemu_strtoll(const char *nptr, const char **endptr, int base,
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int64_t *result)
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@ -376,6 +384,7 @@ int qemu_strtoll(const char *nptr, const char **endptr, int base,
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err = -EINVAL;
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} else {
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errno = 0;
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/* FIXME This assumes int64_t is long long */
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*result = strtoll(nptr, &p, base);
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err = check_strtox_error(nptr, p, endptr, errno);
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}
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@ -383,9 +392,9 @@ int qemu_strtoll(const char *nptr, const char **endptr, int base,
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}
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/**
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* Converts ASCII string to an unsigned long long integer.
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* Convert string @nptr to an uint64_t.
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*
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* See qemu_strtol() documentation for more info.
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* Works like qemu_strtoul(), except it stores UINT64_MAX on overflow.
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*/
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int qemu_strtoull(const char *nptr, const char **endptr, int base,
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uint64_t *result)
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@ -399,6 +408,7 @@ int qemu_strtoull(const char *nptr, const char **endptr, int base,
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err = -EINVAL;
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} else {
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errno = 0;
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/* FIXME This assumes uint64_t is unsigned long long */
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*result = strtoull(nptr, &p, base);
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/* Windows returns 1 for negative out-of-range values. */
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if (errno == ERANGE) {
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