i2c-pseudo: Bring in FROMLIST v3 revision.

This is mostly a copy of:
https://lore.kernel.org/linux-i2c/20200511234817.59365-1-matthewb@google.com/
https://patchwork.ozlabs.org/project/linux-i2c/patch/20200511234817.59365-1-matthewb@google.com/

Changes in this diff:
- Move anprintf() into i2c-pseudo.c.
- Use sizeof_field() instead of FIELD_SIZEOF().
- Add CONST_STRLEN macro for i2cp_cmds[].cmd_size values, because on some
  architectures strlen("literal") is not a compile-time constant.
- Use stream_open() instead of nonseekable_open().
- When copy_from_user() returns non-zero, return -EFAULT instead of 0.

BRANCH=none
BUG=none
TEST=With Linux 5.2:
$ make
$ make clean
$ ./install

Signed-off-by: Matthew Blecker <matthewb@chromium.org>
Change-Id: Idd2b7a2c5630e95de3021c1920ded4cf303db721
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2205293
Reviewed-by: Harry Cutts <hcutts@chromium.org>

2 files changed, 108 insertions, 158 deletions

diff --git a/extra/i2c_pseudo/anprintf.h b/extra/i2c_pseudo/anprintf.h
deleted file mode 100644
index c2d66c494b..0000000000
--- a/extra/i2c_pseudo/anprintf.h
+++ /dev/null
@@ -1,144 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-
-#include <stdarg.h>
-#include <linux/export.h>
-#include <linux/slab.h>
-#include <linux/types.h>
-#include <linux/string.h>
-
-/*
- * vanprintf - Format a string and place it into a newly allocated buffer.
- * @out: Address of the pointer to place the buffer address into.  Will only be
- *     written to with a successful positive return value.
- * @max_size: If non-negative, the maximum buffer size that this function will
- *     attempt to allocate.  If the formatted string including trailing null
- *     character would not fit, no buffer will be allocated, and an error will
- *     be returned.  (Thus max_size of 0 will always result in an error.)
- * @gfp: GFP flags for kmalloc().
- * @fmt: The format string to use.
- * @ap: Arguments for the format string.
- *
- * Return value meanings:
- *
- *   >=0: A buffer of this size was allocated and its address written to *out.
- *        The caller now owns the buffer and is responsible for freeing it with
- *        kfree().  The final character in the buffer, not counted in this
- *        return value, is the trailing null.  This is the same return value
- *        meaning as snprintf(3).
- *
- *    <0: An error occurred.  Negate the return value for the error number.
- *        @out will not have been written to.  Errors that might come from
- *        snprintf(3) may come from this function as well.  Additionally, the
- *        following errors may occur from this function:
- *
- *        ERANGE: A buffer larger than @max_size would be needed to fit the
- *        formatted string including its trailing null character.
- *
- *        ENOMEM: Allocation of the output buffer failed.
- *
- *        ENOTRECOVERABLE: An unexpected condition occurred.  This may indicate
- *        a bug.
- */
-static ssize_t vanprintf(char **out, ssize_t max_size, gfp_t gfp,
-	const char *fmt, va_list ap)
-{
-	int ret;
-	ssize_t buf_size;
-	char *buf = NULL;
-	va_list args1;
-
-	va_copy(args1, ap);
-	ret = vsnprintf(NULL, 0, fmt, ap);
-	if (ret < 0) {
-		pr_err("%s: Formatting failed with error %d.\n", __func__,
-			-ret);
-		goto fail_before_args1;
-	}
-	if (max_size >= 0 && ret > max_size) {
-		ret = -ERANGE;
-		goto fail_before_args1;
-	}
-
-	buf_size = ret + 1;
-	buf = kmalloc(buf_size, gfp);
-	if (buf == NULL) {
-		pr_err("%s: kmalloc(%zd, %u) returned NULL\n", __func__,
-			buf_size, gfp);
-		ret = -ENOMEM;
-		goto fail_before_args1;
-	}
-
-	ret = vsnprintf(buf, buf_size, fmt, args1);
-	va_end(args1);
-	if (ret < 0) {
-		pr_err("%s: Second formatting pass produced error %d after the first pass succeeded.  This is a bug.\n",
-			__func__, -ret);
-		goto fail_after_args1;
-	}
-	if (ret + 1 != buf_size) {
-		pr_err("%s: Second formatting pass produced a different formatted output size than the first.  This is a bug.  Will return -ENOTRECOVERABLE.  first_sans_null=%zd second_sans_null=%d\n",
-			__func__, buf_size - 1, ret);
-		ret = -ENOTRECOVERABLE;
-		goto fail_after_args1;
-	}
-
-	*out = buf;
-	return ret;
-
- fail_before_args1:
-	va_end(args1);
- fail_after_args1:
-	kfree(buf);
-	if (ret >= 0) {
-		pr_err("%s: Jumped to failure cleanup section with non-negative return value %d set.  This is a bug.  Will return -ENOTRECOVERABLE instead.\n",
-			__func__, ret);
-		ret = -ENOTRECOVERABLE;
-	}
-	return ret;
-}
-
-/*
- * anprintf - Format a string and place it into a newly allocated buffer.
- * @out: Address of the pointer to place the buffer address into.  Will only be
- *     written to with a successful positive return value.
- * @max_size: If non-negative, the maximum buffer size that this function will
- *     attempt to allocate.  If the formatted string including trailing null
- *     character would not fit, no buffer will be allocated, and an error will
- *     be returned.  (Thus max_size of 0 will always result in an error.)
- * @gfp: GFP flags for kmalloc().
- * @fmt: The format string to use.
- * @...: Arguments for the format string.
- *
- * Return value meanings:
- *
- *   >=0: A buffer of this size was allocated and its address written to *out.
- *        The caller now owns the buffer and is responsible for freeing it with
- *        kfree().  The final character in the buffer, not counted in this
- *        return value, is the trailing null.  This is the same return value
- *        meaning as snprintf(3).
- *
- *    <0: An error occurred.  Negate the return value for the error number.
- *        @out will not have been written to.  Errors that might come from
- *        snprintf(3) may come from this function as well.  Additionally, the
- *        following errors may occur from this function:
- *
- *        ERANGE: A buffer larger than @max_size would be needed to fit the
- *        formatted string including its trailing null character.
- *
- *        ENOMEM: Allocation of the output buffer failed.
- *
- *        ENOTRECOVERABLE: An unexpected condition occurred.  This may indicate
- *        a bug.
- */
-__attribute__((__format__(__printf__, 4, 5)))
-static ssize_t anprintf(char **out, ssize_t max_size, gfp_t gfp,
-	const char *fmt, ...)
-{
-	ssize_t ret;
-	va_list args;
-
-	va_start(args, fmt);
-	ret = vanprintf(out, max_size, gfp, fmt, args);
-	va_end(args);
-	return ret;
-}
diff --git a/extra/i2c_pseudo/i2c-pseudo.c b/extra/i2c_pseudo/i2c-pseudo.c
index 2fbac6dc1f..69fc9dbc52 100644
--- a/extra/i2c_pseudo/i2c-pseudo.c
+++ b/extra/i2c_pseudo/i2c-pseudo.c
@@ -27,8 +27,7 @@
 #include <linux/types.h>
 #include <linux/uaccess.h>
 #include <linux/wait.h>
-
-#include "anprintf.h"
+#include <stdarg.h>
 
 /* Minimum i2cp_limit module parameter value. */
 #define I2CP_ADAPTERS_MIN	0
@@ -102,8 +101,10 @@ static const char i2cp_ctrlr_data_sep_char	= ':';
 #define STRING_NEQ(in_str, in_size, other_str) \
 	(in_size != strlen(other_str) || memcmp(other_str, in_str, in_size))
 
-#define STR_HELPER(x) #x
-#define STR(x) STR_HELPER(x)
+#define STR_HELPER(num)		#num
+#define STR(num)		STR_HELPER(num)
+
+#define CONST_STRLEN(str)	(sizeof(str) - 1)
 
 /*
  * The number of pseudo I2C adapters permitted.  This default value can be
@@ -657,7 +658,7 @@ struct i2cp_cmd_mxfer_reply_data {
 };
 
 struct i2cp_cmd_set_name_suffix_data {
-	char name_suffix[FIELD_SIZEOF(struct i2c_adapter, name)];
+	char name_suffix[sizeof_field(struct i2c_adapter, name)];
 	size_t name_suffix_len;
 };
 
@@ -754,6 +755,97 @@ struct i2cp_rsp_master_xfer {
 	size_t buf_start_plus_one;
 };
 
+/* vanprintf - See anprintf() documentation. */
+static ssize_t vanprintf(char **out, ssize_t max_size, gfp_t gfp,
+	const char *fmt, va_list ap)
+{
+	int ret;
+	ssize_t buf_size;
+	char *buf = NULL;
+	va_list args1;
+
+	va_copy(args1, ap);
+	ret = vsnprintf(NULL, 0, fmt, ap);
+	if (ret < 0)
+		goto fail_before_args1;
+	if (max_size >= 0 && ret > max_size) {
+		ret = -ERANGE;
+		goto fail_before_args1;
+	}
+
+	buf_size = ret + 1;
+	buf = kmalloc(buf_size, gfp);
+	if (buf == NULL) {
+		ret = -ENOMEM;
+		goto fail_before_args1;
+	}
+
+	ret = vsnprintf(buf, buf_size, fmt, args1);
+	va_end(args1);
+	if (ret < 0)
+		goto fail_after_args1;
+	if (ret + 1 != buf_size) {
+		ret = -ENOTRECOVERABLE;
+		goto fail_after_args1;
+	}
+
+	*out = buf;
+	return ret;
+
+ fail_before_args1:
+	va_end(args1);
+ fail_after_args1:
+	kfree(buf);
+	if (ret >= 0)
+		ret = -ENOTRECOVERABLE;
+	return ret;
+}
+
+/*
+ * anprintf - Format a string and place it into a newly allocated buffer.
+ * @out: Address of the pointer to place the buffer address into.  Will only be
+ *     written to with a successful positive return value.
+ * @max_size: If non-negative, the maximum buffer size that this function will
+ *     attempt to allocate.  If the formatted string including trailing null
+ *     character would not fit, no buffer will be allocated, and an error will
+ *     be returned.  (Thus max_size of 0 will always result in an error.)
+ * @gfp: GFP flags for kmalloc().
+ * @fmt: The format string to use.
+ * @...: Arguments for the format string.
+ *
+ * Return value meanings:
+ *
+ *   >=0: A buffer of this size was allocated and its address written to *out.
+ *        The caller now owns the buffer and is responsible for freeing it with
+ *        kfree().  The final character in the buffer, not counted in this
+ *        return value, is the trailing null.  This is the same return value
+ *        meaning as snprintf(3).
+ *
+ *    <0: An error occurred.  Negate the return value for the error number.
+ *        @out will not have been written to.  Errors that might come from
+ *        snprintf(3) may come from this function as well.  Additionally, the
+ *        following errors may occur from this function:
+ *
+ *        ERANGE: A buffer larger than @max_size would be needed to fit the
+ *        formatted string including its trailing null character.
+ *
+ *        ENOMEM: Allocation of the output buffer failed.
+ *
+ *        ENOTRECOVERABLE: An unexpected condition occurred.  This may indicate
+ *        a bug.
+ */
+static ssize_t anprintf(char **out, ssize_t max_size, gfp_t gfp,
+	const char *fmt, ...)
+{
+	ssize_t ret;
+	va_list args;
+
+	va_start(args, fmt);
+	ret = vanprintf(out, max_size, gfp, fmt, args);
+	va_end(args);
+	return ret;
+}
+
 static ssize_t i2cp_rsp_buffer_formatter(void *data, char **out)
 {
 	struct i2cp_rsp_buffer *rsp_buf;
@@ -1763,7 +1855,7 @@ static int i2cp_cmd_set_timeout_cmd_completer(void *data,
 static const struct i2cp_cmd i2cp_cmds[] = {
 	[I2CP_CMD_MXFER_REPLY_IDX] = {
 		.cmd_string = I2CP_MXFER_REPLY_CMD,
-		.cmd_size = strlen(I2CP_MXFER_REPLY_CMD),
+		.cmd_size = CONST_STRLEN(I2CP_MXFER_REPLY_CMD),
 		.data_creator = i2cp_cmd_mxfer_reply_data_creator,
 		.data_shutdown = i2cp_cmd_mxfer_reply_data_shutdown,
 		.data_destroyer = i2cp_cmd_mxfer_reply_data_destroyer,
@@ -1773,35 +1865,35 @@ static const struct i2cp_cmd i2cp_cmds[] = {
 	},
 	[I2CP_CMD_ADAP_START_IDX] = {
 		.cmd_string = I2CP_ADAP_START_CMD,
-		.cmd_size = strlen(I2CP_ADAP_START_CMD),
+		.cmd_size = CONST_STRLEN(I2CP_ADAP_START_CMD),
 		.header_receiver = i2cp_cmd_adap_start_header_receiver,
 		.data_receiver = i2cp_cmd_adap_start_data_receiver,
 		.cmd_completer = i2cp_cmd_adap_start_cmd_completer,
 	},
 	[I2CP_CMD_ADAP_SHUTDOWN_IDX] = {
 		.cmd_string = I2CP_ADAP_SHUTDOWN_CMD,
-		.cmd_size = strlen(I2CP_ADAP_SHUTDOWN_CMD),
+		.cmd_size = CONST_STRLEN(I2CP_ADAP_SHUTDOWN_CMD),
 		.header_receiver = i2cp_cmd_adap_shutdown_header_receiver,
 		.data_receiver = i2cp_cmd_adap_shutdown_data_receiver,
 		.cmd_completer = i2cp_cmd_adap_shutdown_cmd_completer,
 	},
 	[I2CP_CMD_GET_NUMBER_IDX] = {
 		.cmd_string = I2CP_GET_NUMBER_CMD,
-		.cmd_size = strlen(I2CP_GET_NUMBER_CMD),
+		.cmd_size = CONST_STRLEN(I2CP_GET_NUMBER_CMD),
 		.header_receiver = i2cp_cmd_get_number_header_receiver,
 		.data_receiver = i2cp_cmd_get_number_data_receiver,
 		.cmd_completer = i2cp_cmd_get_number_cmd_completer,
 	},
 	[I2CP_CMD_GET_PSEUDO_ID_IDX] = {
 		.cmd_string = I2CP_GET_PSEUDO_ID_CMD,
-		.cmd_size = strlen(I2CP_GET_PSEUDO_ID_CMD),
+		.cmd_size = CONST_STRLEN(I2CP_GET_PSEUDO_ID_CMD),
 		.header_receiver = i2cp_cmd_get_pseudo_id_header_receiver,
 		.data_receiver = i2cp_cmd_get_pseudo_id_data_receiver,
 		.cmd_completer = i2cp_cmd_get_pseudo_id_cmd_completer,
 	},
 	[I2CP_CMD_SET_NAME_SUFFIX_IDX] = {
 		.cmd_string = I2CP_SET_NAME_SUFFIX_CMD,
-		.cmd_size = strlen(I2CP_SET_NAME_SUFFIX_CMD),
+		.cmd_size = CONST_STRLEN(I2CP_SET_NAME_SUFFIX_CMD),
 		.data_creator = i2cp_cmd_set_name_suffix_data_creator,
 		.data_destroyer = i2cp_cmd_set_name_suffix_data_destroyer,
 		.header_receiver = i2cp_cmd_set_name_suffix_header_receiver,
@@ -1810,7 +1902,7 @@ static const struct i2cp_cmd i2cp_cmds[] = {
 	},
 	[I2CP_CMD_SET_TIMEOUT_IDX] = {
 		.cmd_string = I2CP_SET_TIMEOUT_CMD,
-		.cmd_size = strlen(I2CP_SET_TIMEOUT_CMD),
+		.cmd_size = CONST_STRLEN(I2CP_SET_TIMEOUT_CMD),
 		.data_creator = i2cp_cmd_set_timeout_data_creator,
 		.data_destroyer = i2cp_cmd_set_timeout_data_destroyer,
 		.header_receiver = i2cp_cmd_set_timeout_header_receiver,
@@ -2114,7 +2206,7 @@ static int i2cp_cdev_open(struct inode *inodep, struct file *filep)
 	this_pseudo = i2cp_device;
 
 	/* I2C pseudo adapter controllers are not seekable. */
-	nonseekable_open(inodep, filep);
+	stream_open(inodep, filep);
 	/* Refuse fsnotify events.  Modeled after /dev/ptmx implementation. */
 	filep->f_mode |= FMODE_NONOTIFY;
 
@@ -2810,8 +2902,10 @@ static ssize_t i2cp_cdev_write(struct file *filep, const char __user *buf,
 		ret = -ENOMEM;
 		goto free_kbuf;
 	}
-	if (copy_from_user(kbuf, buf, count))
+	if (copy_from_user(kbuf, buf, count)) {
+		ret = -EFAULT;
 		goto free_kbuf;
+	}
 
 	start = kbuf;
 	remaining = count;